{"affected":[{"defaultStatus":"unaffected","product":"BuildKit","source":"CNA: Docker","vendor":"Moby","versions":[{"lessThan":"0.34.1","status":"affected","version":"0","versionType":"semver"}]}],"cveId":"CVE-2026-121520","cwes":["CWE-61"],"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.","epss":{"date":"2026-11-06","percentile":0.03276,"score":0.00139},"exploits":[],"kev":null,"metrics":[{"score":4.5,"severity":"medium","source":"CNA: Docker","vector":"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","version":"4.0"},{"score":4.5,"severity":"medium","source":"NVD: security@docker.com","vector":"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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X","version":"4.0"}],"modifiedAt":1794001243450,"publishedAt":1793743917202,"references":[{"source":"CNA: Docker","tags":["vendor-advisory"],"url":"https://github.com/moby/buildkit/security/advisories/GHSA-w26x-xg27-7qjc"},{"source":"security@docker.com","tags":[],"url":"https://github.com/moby/buildkit/security/advisories/GHSA-w26x-xg27-7qjc"}],"remediation":[{"kind":"fix","source":"CNA: Docker","text":"Upgrade BuildKit to v0.34.1 or later."},{"kind":"workaround","source":"CNA: Docker","text":"Restrict access to BuildKit control APIs to trusted clients and do not accept build requests from untrusted users."}],"revision":"dc1065e20ed713e5483a1aa7f2daa490e0133e894171dab7f33ea0ceff882cbb","sources":[{"modifiedAt":1793993460151,"name":"CNA: Docker","retrievedAt":1793995830873,"url":"https://www.cve.org/CVERecord?id=CVE-2026-121520"},{"modifiedAt":1794001243450,"name":"NVD","retrievedAt":1794010934931,"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-121520"},{"modifiedAt":null,"name":"FIRST EPSS","retrievedAt":1793995842251,"url":"https://api.first.org/data/v1/epss?cve=CVE-2026-121520"}],"ssvc":{"assessedAt":1793993446298,"automatable":"no","exploitation":"none","source":"ADP: CISA-ADP","technicalImpact":"partial"},"status":"published","title":"Malicious client could set xattr value outside of BuildKit state directory","updatedAt":1794010934931}