From 54315b10e554b5715cc41588ecea19de2017ec39 Mon Sep 17 00:00:00 2001
From: Andras Bacsai <5845193+andrasbacsai@users.noreply.github.com>
Date: Mon, 19 Oct 2026 21:21:15 +0200
Subject: [PATCH] fix(compose): strip UTF-8 BOM before parsing Docker Compose
 YAML (#12223)

---
 bootstrap/helpers/parsers.php                 |  3 +++
 tests/Unit/DockerComposeByteOrderMarkTest.php | 17 +++++++++++++++++
 2 files changed, 20 insertions(+)
 create mode 100644 tests/Unit/DockerComposeByteOrderMarkTest.php

diff --git a/bootstrap/helpers/parsers.php b/bootstrap/helpers/parsers.php
index 21f0d7326d..66330d9d09 100644
--- a/bootstrap/helpers/parsers.php
+++ b/bootstrap/helpers/parsers.php
@@ -26,6 +26,9 @@ use Symfony\Component\Yaml\Yaml;
  */
 function parseDockerComposeYaml(string $compose): mixed
 {
+    // Editors on Windows can save files with a UTF-8 BOM, which Symfony YAML keeps in the first key.
+    $compose = preg_replace('/^\xEF\xBB\xBF/', '', $compose);
+
     return Yaml::parse($compose, maxAliasesForCollections: Application::MAX_DOCKER_COMPOSE_COLLECTION_ALIASES);
 }
 
diff --git a/tests/Unit/DockerComposeByteOrderMarkTest.php b/tests/Unit/DockerComposeByteOrderMarkTest.php
new file mode 100644
index 0000000000..50f94b9812
--- /dev/null
+++ b/tests/Unit/DockerComposeByteOrderMarkTest.php
@@ -0,0 +1,17 @@
+<?php
+
+use Tests\TestCase;
+
+uses(TestCase::class);
+
+it('parses a Docker Compose file that starts with a UTF-8 byte order mark', function () {
+    $compose = "\xEF\xBB\xBFservices:\n  web:\n    image: nginx:alpine\n";
+
+    expect(parseDockerComposeYaml($compose))->toBe([
+        'services' => [
+            'web' => ['image' => 'nginx:alpine'],
+        ],
+    ]);
+
+    validateDockerComposeForInjection($compose);
+});