CVE-2026-33747

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.

CVSS Metrics

• v3.1•HIGH•Score: 8.4CVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
• v3.1•CRITICAL•Score: 9.8CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Trends

Current EPSS score: 0.06%• Percentile: 20%

Techniques & Countermeasures

• CWE-22•Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

  The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.

Affected Systems

• github.com/moby•buildkit

  < 0.28.1

• moby•buildkit

  < 0.28.1

• mobyproject•buildkit

  < 0.28.1

References (4)

• https://github.com/moby/buildkit/security/advisories/GHSA-4c29-8rgm-jvjj
• https://github.com/moby/buildkit
• https://github.com/moby/buildkit/releases/tag/v0.28.1
• https://nvd.nist.gov/vuln/detail/CVE-2026-33747