Critical severity · published Mar 27, 2026
CVE-2026-33747
BuildKit vulnerable to malicious frontend causing file escape outside of storage root
9.8
CVSS
0.5%
EPSS
No
On KEV
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 vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)0.5% · higher than 43% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
BU
buildkit · moby
< 0.28.1 · source: vendor, NVD
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33747
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-33747
Product
https://github.com/moby/buildkit/releases/tag/v0.28.1
Mitigation
https://github.com/moby/buildkit/security/advisories/GHSA-4c29-8rgm-jvjj
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