This release includes 12 security fixes following the security policy:
- net/http: HTTP/1 server crash due to MaxBytesReader header race
For HTTP/1 servers, when MaxBytesReader's limit is exceeded,
"Connection: close" header is automatically set without synchronization,
which might race with another header being set explicitly in the server
handler. As a result, an HTTP/1 server that utilizes MaxBytesReader or
MaxBytesHandler can crash due to runtime panic if its handler reads the
request body concurrently with writing the response header.
Thanks to Jakub Ciolek (https://ciolek.dev) for reporting this issue.
This is CVE-2026-97054 and Go issue https://go.dev/issue/82563.
- cmd/go: unexpected code execution via --sysroot, -target, -isysroot, -Wl,-syslibroot, and -x cgo flags
Building a malicious package that uses cgo could cause arbitrary code execution
at build time through several compiler and linker flags permitted in "#cgo"
directives.
Specifically, "--sysroot" in GCC and Clang relocates compiler subprograms, spec
files, and CRT startup objects to an attacker-controlled directory; "-target" in
Clang falls back to executing target helper tools from the current working
directory when not found in PATH; "-isysroot" and "-Wl,-syslibroot" can pass a
regular file on disk to GNU ld.bfd, which interprets it as a positional linker
script; and "-x" permitted specifying arbitrary compiler input languages beyond
those supported by cgo.
"--sysroot" and "-target" are now disallowed in "#cgo" flags, "-isysroot" and
"-Wl,-syslibroot" are verified not to point to regular files, and "-x" is
restricted to the C, C++, Objective-C, and assembler languages supported by cgo.
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97033 and Go issue https://go.dev/issue/82577.
- cmd/go: arbitrary command execution via GCC spec files in cgo linker search directories
When using GCC, building a malicious package that uses cgo could cause arbitrary
command execution at link time via untrusted GCC spec files ("specs" or
"*.spec").
When linking with "-fopenmp", "-fopenacc", or "-fsanitize=" in "#cgo LDFLAGS",
GCC's built-in link spec evaluates "%:include(libgomp.spec)" or
"%:include(libsanitizer.spec)" and searches for spec files in "-L" and sysroot
directories (including subdirectories and multilib sibling directories such as
"../lib64"), as well as the working directory when "-fopenmp" or "-fopenacc" is
used or when "-fsanitize=" is combined with "-static" or "-static-lib*".
The go command now rejects "-L", "-isysroot", and "-Wl,-syslibroot" directories
(and the working and package directories when applicable) that contain GCC spec
files, and disallows "@" and "-" prefixes in "-fsanitize=" compiler flag values.
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97034 and Go issue https://go.dev/issue/82576.
- cmd/go: unexpected code execution and arbitrary file write via Clang -gen-* and GCC -gnat* flags in cgo
When using Clang or GCC, building a malicious package that uses cgo could cause
unexpected code execution at build time or write files to arbitrary
directories via "-gen-" or "-gnat" flags in "#cgo" directives.
The "-g*" wildcard in the compiler and linker flag allowlists previously
matched Clang's two-argument "-gen-cdb-fragment-path " flag and GCC's
two-argument "-gnatO " flag, permitting compilation database fragments
and sidecar output files to be written to arbitrary directories and
desynchronizing flag argument parsing between the go command and the compiler
driver so that subsequent arguments could be passed as unvalidated positional
inputs to the linker.
"-gen-" and "-gnat" flags are now disallowed in "#cgo" compiler and linker
flags.
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97035 and Go issue https://go.dev/issue/82575.
- cmd/go: arbitrary code execution during build on darwin via "-l to_library" in cgo
On Darwin, building a malicious package that uses cgo could cause arbitrary code
execution when using the Apple linker due to passing "-l to_library " in a
"#cgo LDFLAGS" directive.
The Apple linker recombines the separated arguments "-l" and "to_library" into
"-lto_library", which loads an arbitrary LTO plugin dynamic library at link
time.
The go command now disallows "-l" followed by "to_library" in "#cgo LDFLAGS",
rejects "-lazy_library", "-lazy_framework", "-load_hidden", "-library", and
"-library-path", and checks recombined "-l" arguments against disallowed linker
flags and patterns.
Thanks to Ali Sherif (https://www.linkedin.com/in/ali-sherif-13812b276/) for reporting this issue.
This is CVE-2026-97036 and Go issue https://go.dev/issue/82574.
- cmd/go: linker script injection via split -Wl, flags and Darwin or symbol linker flags in cgo
Building a malicious package that uses cgo could cause arbitrary code execution
at link time by passing linker script files to the host linker via "#cgo LDFLAGS".
Split "-Wl," flags that consume a following argument (such as "-Wl,-rpath",
"-Wl,--just-symbols", and "-Wl,-undefined") previously accepted a bare second
argument without a "-Wl," prefix, which the compiler driver passes directly to
the linker as a positional input file. Additionally, when using GNU ld.bfd,
flags such as "-framework", "-Wl,-framework", "-Wl,-undefined",
"-Wl,--just-symbols", "-Wl,-R", "-Wl,-subsystem", and (on non-Darwin platforms)
"-Wl,-sectcreate" could cause ld.bfd to interpret their arguments as linker
scripts if they named a regular file on disk.
The go command now requires a "-Wl," prefix on the second token of split "-Wl,"
flags (except "-Wl,-R"), verifies that these flags do not reference linker
script files, and disallows bare "-Wl,--warn-backrefs-exclude".
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97037 and Go issue https://go.dev/issue/82573.
- cmd/go: arbitrary code execution via crafted .syso files and cgo linker input files
Building a malicious package containing ".syso" files or cgo linker inputs could
inject arbitrary linker flags or execute arbitrary code at link time.
Linker input files—including ".syso" files, direct object or library inputs in
"#cgo LDFLAGS", and libraries in "-L" directories—were passed to the external
linker without validating their format or checking for embedded linker options.
Across platforms, this allowed executing GNU ld implicit linker scripts
disguised as libraries or ".syso" files (or loaded via "-l:" or "-l"
containing path separators), injecting unallowlisted linker flags via PE/COFF
".drectve" sections on Windows or Mach-O "LC_LINKER_OPTION" load commands on
Darwin, or invoking LTO plugins via GCC or LLVM LTO intermediate representation
sections in ELF, PE/COFF, or Mach-O objects.
The go command now verifies that ".syso" files, direct linker inputs, and
libraries in "-L" directories are valid binary objects or archives that do not
contain unallowlisted ".drectve" directives, "LC_LINKER_OPTION" load commands,
or LTO IR sections, and disallows "-l:" and ":", "=", or path
separators in "-l" flags.
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97038 and Go issue https://go.dev/issue/82572.
- cmd/go: flag sanitization bypass via "#cgo pkg-config:" directives
Building a malicious package that uses "#cgo pkg-config:" directives could
load untrusted pkg-config ".pc" files or inject unvalidated compiler and linker
flags.
The pkg-config flag allowlist previously permitted "--with-path=" and
"--personality=", allowed "--define-variable=" values beginning with "=" or "$"
(which can rewrite paths in system ".pc" files into sysroot-prefixed "-L=" or
"-L$SYSROOT" linker search paths), and allowed package arguments ending in ".pc"
or containing path separators or "..", which caused pkg-config to load local
".pc" files directly from the package directory. In addition, flags returned by
"pkg-config --cflags" in cgoCPPFLAGS were not checked when determining whether
internal linking is safe.
The go command now disallows "--with-path=", "--personality=", leading "=" or
"$" characters in "--define-variable=" values, and local ".pc" paths in
"#cgo pkg-config:" directives, and inspects cgoCPPFLAGS when checking internal
linking compatibility.
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97039 and Go issue https://go.dev/issue/82571.
- cmd/go, cmd/link: cgo directive injection via .syso files disguised as Go object files
Building a package containing a crafted ".syso" file could bypass cgo flag
validation and inject arbitrary linker flags when linking.
When loading ".syso" entries from a package archive, the linker only checked for
recognized host object headers (ELF, Mach-O, PE, and XCOFF) before falling
through to Go object parsing. A ".syso" file beginning with a "go object" header
was parsed as a Go compiler object, allowing untrusted cgo metadata directives
(such as "cgo_ldflag" or "cgo_dynamic_linker") embedded in the ".syso" file to
be passed to the external linker without validation. Additionally, ".syso"
filenames longer than 16 bytes lost their ".syso" extension when truncated in
archive headers, and unrecognized ".syso" formats forced external linking in
pure-Go builds.
The linker now rejects ".syso" files that are not recognized host object
formats, and "cmd/go" and "cmd/pack" preserve the ".syso" suffix when truncating
long archive member names.
Thanks to RyotaK (https://ryotak.net) of GMO Flatt Security Inc. for reporting this issue.
This is CVE-2026-97040 and Go issue https://go.dev/issue/82570.
- cmd/compile, cmd/link: host linker flag injection via //go:cgo_* directives
Building a malicious package containing "//go:cgo_*" compiler directives could
inject arbitrary flags into the external linker invocation on ELF platforms.
The compiler and linker did not reject commas in "//go:cgo_import_dynamic",
"//go:cgo_export_dynamic", "//go:cgo_export_static", "//go:cgo_import_static",
and "//go:cgo_dynamic_linker" directives, and the linker passed the dynamic
linker path using "-Wl,--dynamic-linker,". Furthermore, the two-argument
form of "//go:cgo_import_dynamic" (which is permitted in non-cgo Go source
files) could overwrite the external symbol name of a symbol already marked for
cgo export. A symbol name or dynamic linker path containing a comma or leading
"@" could split "-Wl,--export-dynamic-symbol=" or "-Wl,--dynamic-linker," into
arbitrary host linker flags or response file arguments.
The compiler and linker now reject commas in "//go:cgo_*" symbol and dynamic
linker directives, the linker passes "-Wl,--dynamic-linker=", and
"cgo_import_dynamic" no longer overwrites symbols exported via
"cgo_export_dynamic" or "cgo_export_static".
Thanks to RyotaK (https://ryotak.net) of GMO Flatt Security Inc. for reporting this issue.
This is CVE-2026-97041 and Go issue https://go.dev/issue/82569.
- cmd/cgo, cmd/compile, cmd/link: linker flag injection via cgo_import_dynamic and PE DLL names
Building a malicious package that uses "//go:cgo_import_dynamic" or links
against a crafted PE object on Windows could pass unsafe library arguments to
the external linker.
The compiler only checked the first character of the library name in
"//go:cgo_import_dynamic" directives and skipped validation in cgo-generated
files. In addition, on Windows, "cmd/cgo" and "cmd/link" did not validate
imported DLL names extracted from PE object files before emitting "-l"
flags for the external linker, allowing a crafted DLL name containing ".." path
traversal or special characters to reference arbitrary files on disk.
The compiler now validates every character of the library name in
"//go:cgo_import_dynamic" directives (including in cgo-generated files on
Windows) and rejects ".." path traversal, and "cmd/cgo" and "cmd/link" reject
PE imported DLL names containing path separators, "..", ":", or leading "-" or
"@".
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97042 and Go issue https://go.dev/issue/82568.
- cmd/go, cmd/compile: unexpected code execution via escaped quotes in //go:cgo_ldflag
Building a malicious package that uses cgo could bypass "#cgo LDFLAGS"
validation and cause unexpected code execution at build time, or cause the go
command to panic, via crafted quoting in "//go:cgo_ldflag" directives.
When "cmd/cgo" generates "_cgo_gotypes.go", it quotes each "#cgo LDFLAGS"
argument with strconv.Quote in a "//go:cgo_ldflag" directive, but "cmd/compile"
and "cmd/go" parsed those directives by splitting on raw quote characters
without handling backslash escapes or unquoting the string. This mismatch
allowed disallowed linker flags or unvalidated linker search paths to be
smuggled past the go command's flag checks and passed to the external linker.
In addition, deduplicating LDFLAGS in the go command could panic with an
out-of-bounds slice index when a prefix of the flag list matched near the end
of the slice.
"cmd/compile" and "cmd/go" now properly handle backslash-escaped quotes and
unquote "//go:cgo_*" pragma strings with strconv.Unquote, and the slice bounds
check in processCgoOutputs has been fixed.
This issue was found by the Go Security Team during an internal audit.
This is CVE-2026-97043 and Go issue https://go.dev/issue/82567.
release notes: https://go.dev/doc/devel/release#go1.27.4
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
GitHub Actions retired macOS 14 runners on November 2, 2026.
Replace macos-14 with macos-26 to continue testing on supported
macOS versions.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
follow-up to 18958e4c02, which updated
the e2e workflow, but forgot to update the other workflows.
Replace the CODECOV_TOKEN secret with GitHub Actions OIDC authentication.
Codecov supports tokenless uploads for public repositories, but
authenticated uploads are still needed to protect coverage results on
protected branches from unauthorized uploads.
Grant `id-token: write` at the job level to allow Codecov to request
a short-lived OIDC token. This permission does not grant repository
write access, and scoping it to the job avoids granting it to other
jobs added to the workflow in the future.
Coverage uploads from forked pull requests continue to use Codecov's
tokenless upload mechanism.
See https://github.com/codecov/codecov-action/blob/v7.1.1/README.md#using-oidc
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
Replace the CODECOV_TOKEN secret with GitHub Actions OIDC authentication.
Codecov supports tokenless uploads for public repositories, but
authenticated uploads are still needed to protect coverage results on
protected branches from unauthorized uploads.
Grant `id-token: write` at the job level to allow Codecov to request
a short-lived OIDC token. This permission does not grant repository
write access, and scoping it to the job avoids granting it to other
jobs added to the workflow in the future.
Coverage uploads from forked pull requests continue to use Codecov's
tokenless upload mechanism.
See https://github.com/codecov/codecov-action/blob/v7.1.1/README.md#using-oidc
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
This release includes 1 security fix following the security policy:
- crypto/x509: mitigation for security concerns with a specific Certificate Authority
We're blocking trust in a small set of intermediate certificates due to specific security concerns around their operation.
Verify will now filter out chains which contain these intermediates, preventing them from being returned to the caller.
We highly recommend immediately upgrading to this release.
This is CVE-2026-111943 and Go issue https://go.dev/issue/82345.
release notes: https://go.dev/doc/devel/release#go1.26.10
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
This release includes 15 security fixes following the security policy:
- net/http: HTTP/2 server crash due to HPACK encoder race
HTTP/2 servers could end up crashing due to inadvertently
modifying its HPACK encoder concurrently. This happens because the
server modifies the HPACK encoder from two goroutines without
synchronization: one uses the encoder to encode a HEADERS frame as part
of a response sent to a client and the other modifies the encoder's
table size when handling a SETTINGS frame containing
SETTINGS_HEADER_TABLE_SIZE that a client sends. A malicious client can
repeatedly send a request while changing the header table size to crash
the server.
Fix this issue by not applying SETTINGS_HEADER_TABLE_SIZE immediately.
Instead, buffer any SETTINGS_HEADER_TABLE_SIZE received, and only apply
the new value prior to the next time the server writes a frame.
Thanks to RyotaK (https://ryotak.net) of GMO Flatt Security Inc. for reporting this issue.
This is CVE-2026-97032 and Go issue https://go.dev/issue/81867.
- net/http: HTTP/2 server memory exhaustion due to Trailer headers
When "Trailer" headers are sent by a client, the HTTP server internally
uses the header values to populate the Request.Trailer map passed to the
server handler. Because Request.Trailer is a map, each entry incurs
memory overhead. For HTTP/2 servers, a malicious client can exploit this
by sending a "Trailer" header that declares a large number of fields,
causing the server to allocate a disproportionate amount of memory while
bypassing Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits.
This exploit is not applicable for HTTP/1 servers, which do not support
multiplexing a large number of requests over one TCP connection, and
whose Server.MaxHeaderBytes are calculated differently.
Server.MaxHeaderValueCount and Server.MaxHeaderBytes limits are now
applied towards the trailer fields declared in "Trailer" headers.
Thanks to RyotaK (https://ryotak.net) of GMO Flatt Security Inc. for reporting this issue.
This is CVE-2026-78659 and Go issue https://go.dev/issue/81857.
- crypto/tls: reject malformed ECH outer extension references
Multiple ECH outer extension references are not
permitted under RFC 9849; previously, a client
could send a well-crafted packet that could
trigger memory exhaustion in the server process
by specifying multiple references.
We now reject these as malformed and curb the
memory amplification vector as a result.
This is CVE-2026-97031 and Go issue https://go.dev/issue/81855.
- cmd/go: checksum bypass for golang.org/fips140
Previously, a user operating inside of a malicious
Go project that defines a bogus golang.org/fips140
and operates a malicious GOMODPROXY the user chooses
to connect to can serve an arbitrary module in its
place.
We now unpack the trusted ziphash for the bundled
golang.org/fips140 module and construct its entry
in the GOMODCACHE such that it can be verified by
the toolchain.
This is CVE-2026-94444 and Go issue https://go.dev/issue/81833.
- cmd/go: checksum database bypass for golang.org/toolchain
Previously, a user operating inside of a malicious
Go project that defines a bogus golang.org/toolchain
go.sum entry and operates a malicious GOMODPROXY the
user chooses to use can bypass the intended checksum.
We now ensure that golang.org/toolchain always goes
to the network for the canonical checksum.
This is CVE-2026-94447 and Go issue https://go.dev/issue/81834.
- html/template: reset context tracking on consecutive template expressions
When a JavaScript template literal contains
consecutive expressions, the context tracking
state was not properly reset upon entering a
new expression.
We now ensure that template-literal expression
entries correctly reset context variables so all
subsequent regular expression literals are
accurately recognized and escaped.
This is CVE-2026-94448 and Go issue https://go.dev/issue/81821.
- html/template: recognize yield as regexp preceder keyword
A trusted template author may have previously
written a valid template wherein the use of
the yield keyword would not be correctly
escaped.
We now ensure that valid keyword uses are
escaped and non-keyword uses are not escaped.
This is CVE-2026-97030 and Go issue https://go.dev/issue/81823.
- net/textproto, mime/multipart: memory limit bypass when parsing MIME headers
Parsing a multipart form could bypass memory limits and read an
arbitrarily long line into memory when the remaining limit at the
start of a part was less than 400 bytes.
Multipart form memory limits are now properly enforced in this situation.
Thanks to Jakub Ciolek (https://ciolek.dev) for reporting this issue.
This is CVE-2026-94440 and Go issue https://go.dev/issue/81741.
- net/http: HTTP/1 client connection desynchronization after CONNECT rejection
When http.Transport sends an HTTP/1 CONNECT request with a non-empty
Request.Body, it writes the body directly to the connection without
framing after the request headers. If the server rejects the CONNECT
request with a non-2xx keep-alive response, Transport returns the
connection to the idle pool. Because CONNECT requests do not have a
request body, the server may interpret the trailing body bytes as a
subsequent pipelined HTTP/1.1 request on the connection, leaving the
pooled connection desynchronized and causing the next caller that reuses
it to read the response to the injected request. In reverse proxies
(including httputil.ReverseProxy) that forward CONNECT requests through
a shared Transport, this can lead to cross-user response poisoning.
The HTTP/1 transport now closes a connection after sending a CONNECT
request, regardless of the response status.
In addition, ReverseProxy now rejects incoming CONNECT requests
with a 405 Method Not Allowed response. ReverseProxy has never handled
CONNECT requests in a useful fashion (it does not convert the
connection into a bidirectional tunnel), so we do not expect this
change to negatively affect any current users.
Thanks to Xclow3n (Rajat Raghav) for reporting this issue.
This is CVE-2026-56866 and Go issue https://go.dev/issue/81740.
- net/http: HTTP/1 server connection desynchronization after 2xx CONNECT response
When an HTTP server handler sent a 2xx response to an HTTP/1 CONNECT request
and returned without hijacking the connection, the server improperly continued
to read and serve requests from the connection. Since a 2xx response to an
HTTP/1 CONNECT converts the connection into a tunnel, the server should not
treat the connection as continuing to contain HTTP.
The impact of this misbehavior is mostly limited to potential request smuggling,
where an intermediate proxy considers the data on the connection to be tunneled
and the server considers it to be HTTP.
The HTTP/1 server now always closes a connection after responding to a CONNECT
request, regardless of the response status.
Thanks to Jakub Ciolek (https://ciolek.dev) for reporting this issue.
This is CVE-2026-94439 and Go issue https://go.dev/issue/81744.
- net/http: excessive CPU consumption from repeated initial window changes
A malicious HTTP/2 peer could cause excessive CPU consumption in the
client or server by opening a large number of streams and then sending
many small SETTINGS frames containing SETTINGS_INITIAL_WINDOW_SIZE values.
The HTTP/2 client and server now efficiently handle changes to the
initial window size (O(1) rather than O(number of streams)).
Thanks to Jakub Ciolek (https://ciolek.dev) for reporting this issue.
This is CVE-2026-78669 and Go issue https://go.dev/issue/81742.
- net/http: HTTP/2 transport accepts malformed framing-related headers
Historically, we have been rather lax about malformed framing-related
headers in our HTTP/2 implementation, as they cannot interfere with
HTTP/2 framing. However, this makes it possible for our HTTP/2
implementation to forward responses containing such headers to an HTTP/1
client when acting as a reverse proxy. If the HTTP/1 client also does
not behave strictly enough, this can result in response smuggling.
We now delete malformed framing-related headers when received by our
HTTP/2 transport, so they will not be forwarded to a potentially
vulnerable HTTP/1 client.
Thanks to TJ Barton for reporting this issue.
This is CVE-2026-78660 and Go issue https://go.dev/issue/81115.
- os: Root.Mkdir(All) can follow junctions out of the root on Windows
On Windows, when the target of Root.Mkdir or Root.MkdirAll was a junction
pointing to an empty location, the operation would create a directory at
the junction target even when that target was located outside the root.
This only applies to operations where the last path component is a
junction (path/to/junction, but not path/junction/target).
Root.Mkdir and Root.MkdirAll now correctly avoid resolving junctions.
Thanks to Daniele Ballarini for reporting this issue.
This is CVE-2026-56857 and Go issue https://go.dev/issue/81739.
- net/http: lack of limit on size of parsed Range headers
When parsing a Range header containing a large number of small ranges,
FileServer(FS), ServeContent, and ServeFile(FS) could consume an excessive
amount of CPU.
These functions now ignore Range headers containing more than 200 ranges.
The limit is controlled by the new httpservecontentmaxranges=
GODEBUG setting. Setting GODEBUG=httpservecontentmaxranges=0
disables the limit.
Thanks to Jakub Ciolek (https://ciolek.dev) for reporting this issue.
This is CVE-2026-78667 and Go issue https://go.dev/issue/81858.
- net/http: double flow control refund on HTTP/2 server streams
The HTTP/2 server could refund connection-level flow control twice for the same data:
Once when a client resets a stream (refunding data for any sent-but-unread portion
of the stream), and again when a request handler reads the buffered data.
A malicious client could exploit this to bypass the configured connection-level
flow control limit (MaxReceiveBufferPerConnection). Total buffered data is still
limited by the concurrent stream limit and stream-level flow control.
The HTTP/2 server now waits to refund connection-level flow control for reset
streams until after the request handler is complete.
Thanks to Ali Sherif (https://www.linkedin.com/in/ali-sherif-13812b276/) for reporting this issue.
This is CVE-2026-78663 and Go issue https://go.dev/issue/81743.
release notes: https://go.dev/doc/devel/release#go1.26.9
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
Add a "master" engine-version to the e2e matrix to catch regressions
against the upcoming engine release before it reaches an rc.
There is no "master" dind image, so just copy the engine binary from the
moby/moby-bin:master image and put it into the latest dind image.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
This release includes a fix to address a breakage affecting unencrypted
HTTP/2 (h2c) connections caused by a security patch included in last
patch release.
See go.dev/issue/80876 for details.
Signed-off-by: Paweł Gronowski <pawel.gronowski@docker.com>
This release includes 10 security fixes following the security policy:
- x/mod/sumdb/tlog: fix transparency log tile verification bypass
A malicious GOPROXY was previously capable of forging
up to two sumdb tiles that allow for a requested module
to bypass the GOSUMDB check and persist attacker-controlled
module content to a local Go module cache.
This attack allows for a malicious GOPROXY to serve
malicious module content that cannot be detected
by evaluating the transparency log.
All tiles are now correctly verified against their parents.
In order to determine if you have been affected:
rm -r go.sum go.work.sum vendor/ && go mod tidy
Thanks to Filippo Valsorda (Geomys) for reporting this issue.
This is CVE-2026-56865 and Go issue https://go.dev/issue/80744.
- x/mod/sumdb: ignore unrelated, unauthenticated hashes in Lookup
A malicious GOSUMDB was capable of serving arbitrary
module content not contained within the transparency
log.
This attack allows for a coordinating GOPROXY and
GOSUMDB to serve a client malicious module content
that cannot be detected by evaluating the transparency
log.
In order to determine if you have been affected:
rm -r go.sum go.work.sum vendor/ && go mod tidy
Thanks to mundur for reporting this issue.
This is CVE-2026-56864 and Go issue https://go.dev/issue/80745.
- encoding/xml: add recursion depth guard during decode
Previously, DecodeElement would reset the depth counter
causing it to never fire; this could lead to stack
exhaustion.
This is CVE-2026-56859 and Go issue https://go.dev/issue/80481.
net/http: apply ReadHeaderTimeout when doing unencrypted HTTP/2 check
When a server is configured to support unencrypted HTTP/2, it reads a
few bytes from each new connection to see if they contain the HTTP/2
client preface. Previously, this was being done with no timeout applied.
ReadHeaderTimeout is now applied for this.
This is CVE-2026-56853 and Go issue https://go.dev/issue/80205.
- net/url: avoid quadratic complexity in resolvePath
Previously, resolving relative paths containing parent directory (..) segments performed string conversions and buffer rewrites on each step, resulting in quadratic time complexity and high memory allocation overhead.
Now, path resolution operates on a byte buffer using index-based backtracking for .. segments, eliminating the quadratic time complexity and significantly reducing memory allocations.
This is CVE-2026-56860 and Go issue https://go.dev/issue/80494.
- golang.org/x/net/dns/dnsmessage: panic when parsing invalid SVCB record
Parsing an invalid SVCB or HTTPS RR can panic when
the size of a parameter value overflows the message buffer.
Thanks to Mundur (https://github.com/M0nd0R) for reporting this issue.
This is CVE-2026-46600 and Go issue https://go.dev/issue/79795.
- crypto/tls: limit handshake messages we are willing to accept post-handshake
Previously, we always counted handshake messages, such as KeyUpdate, as
state-advancing, regardless of whether a handshake has been completed or
not. As a result, a malicious client can keep sending KeyUpdate messages
to force the server to keep performing key derivation operations
indefinitely.
Thanks to Qi Deng of Aurascape.ai for reporting this issue.
This is CVE-2026-56862 and Go issue https://go.dev/issue/80528.
- html/template: fix Javascript regexp context tracking
Previously, pathological inputs could close an
unescaped / early, allowing for attack-controlled
data to inject arbitrary content, potentially
leading to XSS.
Thanks to Ali Sherif for reporting this issue.
This is CVE-2026-56858 and Go issue https://go.dev/issue/80435.
- x/net/idna: failure to reject ASCII-only Punycode-encoded labels
The ToASCII and ToUnicode functions incorrectly accepted Punycode-encoded labels
that decode to an ASCII-only label. For example, ToUnicode("xn--example-.com")
incorrectly returned the name "example.com" rather than an error.
The idna package implements the processing algorithm from UTS 46.
Older versions of UTS 46 included a specification bug which permitted
multiple ASCII labels to decode to the same Unicode label.
UTS 46 revision 33 fixed the specification bug.
The idna package now implements the updated specification.
This behavior can lead to privilege escalation in programs using the idna package.
For example, a program which performs privilege checks on the ASCII hostname
may reject "example.com" but permit "xn--example-.com". If that program subsequently
converts the ASCII hostname to Unicode, it will inadvertently permits access
to the Unicode name "example.com".
Thanks to KC1zs4 (https://github.com/KC1zs4) for reporting this issue.
This is CVE-2026-39821 and Go issue https://go.dev/issue/78760.
- encoding/asn1: enforce maximum recursion depth
Enforce a recursion limit in Unmarshal to prevent stack exhaustion
when parsing deeply-nested, recursive structures.
Thanks to Marwan Atia (marwans...@gmail.com) for reporting this issue.
This is CVE-2026-33818 and Go issue https://go.dev/issue/80405.
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>
dependabot[bot]
Paweł Gronowski
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Sebastiaan van Stijn
Sebastiaan van Stijn