{"id":"CVE-2026-121520","title":"Malicious client could set xattr value outside of BuildKit state directory","summary":"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 trus…","severity":"medium","cvss":4.5,"cvssVector":"CVSS:4.0/AV:L/AC:L/AT:P/PR:H/UI:N/VC:N/VI:N/VA:N/SC:N/SI:H/SA:H","cvssSource":"cna","cwe":["CWE-61"],"vendor":"Moby","product":"BuildKit","affected":["BuildKit < 0.34.1"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T19:30:46.298631Z"},"published":"2026-11-03","updated":"2026-11-06","sourceUpdated":"2026-11-06T19:31:00.151Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-121520","references":[{"url":"https://github.com/moby/buildkit/security/advisories/GHSA-w26x-xg27-7qjc"}],"tags":["cve.org"],"epss":0.00139,"epssPercentile":0.03266,"ingestedAt":"2026-11-05T20:33:06.571Z","slug":"CVE-2026-121520","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `BuildKit < 0.34.1`\n\n## Remediation\n\nUpgrade BuildKit to v0.34.1 or later.\n\n### Workarounds\n\nRestrict access to BuildKit control APIs to trusted clients and do not accept build requests from untrusted users.","depth":"sunlit","depthScore":25,"depthScoreParts":{"impact":24.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}