[ CVE-2026-121520 · Published 3 Nov 2026 ]
Vulnerability in Moby BuildKit
CVSS 4.5
EPSS <1%1 agency advisoryNo fix listed yet
[ Description ]Official description
In BuildKit versions prior to v0.34.1, a malicious client with access to the BuildKit control APIs can submit a build request that sets an extended attribute on a file outside the BuildKit state directory. Extended attributes in the trusted. or security. namespaces may also be set, potentially giving a program on the host elevated privileges. This issue affects build services that accept build requests from untrusted users. The issue is fixed in v0.34.1.
[ Fixes ]Fixes and patches
No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.
[ Advisories ]Government CERT advisories
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BSI CERT-BundWID-SEC-2026-4338
BuildKit: Multiple vulnerabilities Translated from German