BuildKit vulnerable to malicious frontend causing file escape outside of storage root

MITRE NVD CVE.ORG Print: PDF PDF

Summary

CVECVE-2026-33747
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-03-27 01:16:21 UTC
Updated2026-04-01 14:34:48 UTC
DescriptionBuildKit 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.

Risk And Classification

Primary CVSS: v3.1 9.8 CRITICAL from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS: 0.000060000 probability, percentile 0.004280000 (date 2026-04-01)

Problem Types: CWE-22 | CWE-22 CWE-22: Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

VersionSourceTypeScoreSeverityVector
3.1[email protected]Primary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1[email protected]Secondary8.4HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.1CNADECLARED8.4HIGHCVSS:3.1/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Application Mobyproject Buildkit All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Moby Buildkit affected < 0.28.1 Not specified

References

ReferenceSourceLinkTags
github.com/moby/buildkit/releases/tag/v0.28.1 [email protected] github.com Product, Release Notes
github.com/moby/buildkit/security/advisories/GHSA-4c29-8rgm-jvjj [email protected] github.com Mitigation, Vendor Advisory
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NVD vulnerability detail NVD nvd.nist.gov canonical, analysis
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