diff --git a/.changes/restricted-preview-changes-rollbacks-and-repository.md b/.changes/restricted-preview-changes-rollbacks-and-repository.md
index 0f29546f3b..f910912ae8 100644
--- a/.changes/restricted-preview-changes-rollbacks-and-repository.md
+++ b/.changes/restricted-preview-changes-rollbacks-and-repository.md
@@ -7,3 +7,4 @@ Restricted preview changes, rollbacks and repository URL changes
 - Opening a preview, changing its pull request URL, Git type or Docker tag, or choosing a commit through the API needs write access, a deploy token can only redeploy an existing preview
 - A rollback goes only to a listed rollback image or a successful production deployment
 - A new `git_repository` of an application is validated like in the UI
+- The `docker_tag` of `/api/v1/deploy` is validated like in the preview API
diff --git a/app/Http/Controllers/Api/DeployController.php b/app/Http/Controllers/Api/DeployController.php
index 1fbea69088..589e838834 100644
--- a/app/Http/Controllers/Api/DeployController.php
+++ b/app/Http/Controllers/Api/DeployController.php
@@ -17,6 +17,7 @@ use App\Models\Service;
 use App\Models\Tag;
 use App\Services\Access\AccessResolver;
 use App\Support\ResourceStartActivity;
+use App\Support\ValidationPatterns;
 use Illuminate\Auth\Access\AuthorizationException;
 use Illuminate\Http\Request;
 use OpenApi\Attributes as OA;
@@ -405,6 +406,9 @@ class DeployController extends Controller
         if ($tags && $pr) {
             return response()->json(['message' => 'You can only use tag or pr, not both.'], 400);
         }
+        if (! ValidationPatterns::isValidDockerImageTag($dockerTag, allowVariables: false)) {
+            return response()->json(['message' => 'docker_tag must be a valid Docker tag: letters, digits, underscores, periods, and dashes, at most 128 characters.'], 400);
+        }
         if ($dockerTag && $pr === 0) {
             return response()->json(['message' => 'docker_tag requires pull_request_id.'], 400);
         }
diff --git a/tests/Feature/DockerImagePreviewDeploymentApiTest.php b/tests/Feature/DockerImagePreviewDeploymentApiTest.php
index b63b26634b..0857ddbee0 100644
--- a/tests/Feature/DockerImagePreviewDeploymentApiTest.php
+++ b/tests/Feature/DockerImagePreviewDeploymentApiTest.php
@@ -126,6 +126,20 @@ test('it rejects docker_tag without pull_request_id', function () {
     $response->assertJson(['message' => 'docker_tag requires pull_request_id.']);
 });
 
+test('it rejects a docker_tag that is not a valid docker tag', function (string $dockerTag) {
+    $application = createDockerImageApplication($this->environment, $this->destination);
+
+    $this->withHeaders(['Authorization' => 'Bearer '.$this->bearerToken])->postJson('/api/v1/deploy', [
+        'uuid' => $application->uuid,
+        'pull_request_id' => 5,
+        'docker_tag' => $dockerTag,
+    ])->assertStatus(400)
+        ->assertJson(['message' => 'docker_tag must be a valid Docker tag: letters, digits, underscores, periods, and dashes, at most 128 characters.']);
+
+    expect($application->previews()->count())->toBe(0)
+        ->and($application->deployment_queue()->count())->toBe(0);
+})->with(['-leading-dash', 'a;id', '$TAG', 'a:b', str_repeat('a', 129)]);
+
 test('it rejects docker_tag for non docker image applications', function () {
     $application = Application::factory()->create([
         'uuid' => (string) Str::uuid(),