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HIGH severity

BuildKit's Malicious frontend can cause file escape outside of storage rootGHSA-4c29-8rgm-jvjj

HIGH

GHSA-4c29-8rgm-jvjj is a high-severity (CVSS 8.4) Path Traversal vulnerability in github.com/moby/buildkit. A fix is available for github.com/moby/buildkit — see the affected versions and patch details below.

Also known asCVE-2026-33747GO-2026-4858
Published
Updated
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Nov 11, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • A successful exploit gives an attacker total control of the affected component, not partial access.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-4c29-8rgm-jvjj.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs44th percentile — riskier than 44% of all scored CVEsHighest risk
0.00%0.36%0.72%1.08%0.1%0.5%May 26Sep 26Nov 26

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

1 pkg affected
🐹github.com/moby/buildkit

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Go packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐹Gogithub.com/moby/buildkitall versions0.28.1go get github.com/moby/buildkit@v0.28.1

Affected Products

1 product · 1 configurations
Application
buildkitmobyproject
< 0.28.1
range

Detection & mitigation playbook

Open-source dependency

  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for github.com/moby/buildkit, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update github.com/moby/buildkit to 0.28.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4c29-8rgm-jvjj is resolved across your whole dependency graph.

  3. Workarounds

    Resolve every user-supplied path to its canonical form and reject anything that escapes the intended directory, and run the component under an account that has no read or write access outside the directory it legitimately serves.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

An arbitrary file write vulnerability with moderate impact was found in BuildKit, a toolkit for converting source code into build artifacts that is used by a wide range of Red Hat products and container images. When a build explicitly selects an untrusted custom BuildKit frontend, set through the `#syntax` Dockerfile…

Workaround published by Red Hat
To mitigate this vulnerability, avoid using untrusted BuildKit frontends. Restrict the use of custom BuildKit frontends to only those from verified and trusted sources. Do not specify untrusted frontends via `#syntax` or `--build-arg BUILDKIT_SYNTAX`.
Source: Red Hat security advisory for GHSA-4c29-8rgm-jvjj (CC BY 4.0)
ProductFixed inAdvisory
multicluster engine for Kubernetes 2.10multicluster-engine/must-gather-rhel9:1784849867RHSA-2026:46885
multicluster engine for Kubernetes 2.10multicluster-engine/must-gather-rhel9:1784849867RHSA-2026:47388
multicluster engine for Kubernetes 2.8multicluster-engine/must-gather-rhel9:1782158798RHSA-2026:30650
OpenShift API for Data Protection 1.3oadp/oadp-mustgather-rhel9:1785177359RHSA-2026:51033
OpenShift API for Data Protection 1.4oadp/oadp-mustgather-rhel9:1779770049RHSA-2026:29854
OpenShift API for Data Protection 1.5oadp/oadp-mustgather-rhel9:1779770057RHSA-2026:26568
Red Hat OpenShift AI 2.25rhoai/odh-pipeline-runtime-datascience-cpu-py312-rhel9:1783696512RHSA-2026:42644
Red Hat Openshift Data Foundation 4.20odf4/cephcsi-rhel9:1786627460RHSA-2026:57013
UbuntuHIGH
USN-8230-1Ubuntu

Frequently Asked Questions

### 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.
O3 Security · Impact-Aware SCA

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