BuildKit's Malicious frontend can cause file escape outside of storage root

CRITICAL 9.8CVE-2026-33747 · GHSA-4c29-8rgm-jvjj · GO-2026-4858 · Published 27/03/2026 · updated 17/06/2026

Package	Affected versions	Patched versions
github.com/moby/buildkit Go	`< 0.28.1`	`0.28.1`
buildkit mobyproject	`< 0.28.1`	`0.28.1`

Description

Impact

When using a custom BuildKit frontend, the frontend can craft an API message that causes files to be written outside of the BuildKit state directory for the execution context.

Patches

The issue has been fixed in v0.28.1+

Workarounds

Issue requires using an untrusted BuildKit frontend set with #syntax or --build-arg BUILDKIT_SYNTAX. Using these options with a well-known frontend image like docker/dockerfile is not affected.

NVD description

BuildKit is a toolkit for converting source code to build artifacts in an efficient, expressive and repeatable manner. Prior to version 0.28.1, when using a custom BuildKit frontend, the frontend can craft an API message that causes files to be written outside of the BuildKit state directory for the execution context. The issue has been fixed in v0.28.1. The vulnerability requires using an untrusted BuildKit frontend set with `#syntax` or `--build-arg BUILDKIT_SYNTAX`. Using these options with a well-known frontend image like `docker/dockerfile` is not affected.

References

moby/buildkit security advisory · WEB
nvd.nist.gov/vuln/detail/CVE-2026-33747 · ADVISORY
moby/buildkit · PACKAGE
moby/buildkit release v0.28.1 · WEB

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Package

Affected versions

Patched versions

github.com/moby/buildkit

< 0.28.1

0.28.1

buildkit

mobyproject

< 0.28.1

0.28.1

Description

Impact

When using a custom BuildKit frontend, the frontend can craft an API message that causes files to be written outside of the BuildKit state directory for the execution context.

Patches

The issue has been fixed in v0.28.1+

Workarounds

Issue requires using an untrusted BuildKit frontend set with #syntax or --build-arg BUILDKIT_SYNTAX. Using these options with a well-known frontend image like docker/dockerfile is not affected.

NVD description