{"id":"CVE-2026-56857","sourceIdentifier":"security@golang.org","published":"2026-10-08T23:17:01.487","lastModified":"2026-10-09T16:35:35.900","vulnStatus":"Awaiting Analysis","cveTags":[],"descriptions":[{"lang":"en","value":"On Windows, when the target of Root.Mkdir or Root.MkdirAll is a junction pointing to an empty location, the operation can create a directory at the junction target even when that target is located outside the root. This only applies to operations where the last path component is a junction (path/to/junction, but not path/junction/target)."}],"affected":[{"source":"security@golang.org","affectedData":[{"vendor":"Go standard library","product":"os","defaultStatus":"unaffected","collectionURL":"https://pkg.go.dev","packageName":"os","platforms":["windows"],"programRoutines":[{"name":"Root.Mkdir"},{"name":"doInRoot"},{"name":"rootMkdirAll"},{"name":"Root.Chmod"},{"name":"Root.Chown"},{"name":"Root.Chtimes"},{"name":"Root.Lchown"},{"name":"Root.Link"},{"name":"Root.MkdirAll"},{"name":"Root.Remove"},{"name":"Root.RemoveAll"},{"name":"Root.Rename"},{"name":"Root.Symlink"}],"versions":[{"version":"0","lessThan":"1.26.9","versionType":"semver","status":"affected"},{"version":"1.27.0-0","lessThan":"1.27.2","versionType":"semver","status":"affected"}]},{"vendor":"Go standard library","product":"internal/syscall/windows","defaultStatus":"unaffected","collectionURL":"https://pkg.go.dev","packageName":"internal/syscall/windows","platforms":["windows"],"programRoutines":[{"name":"Mkdirat"}],"versions":[{"version":"0","lessThan":"1.26.9","versionType":"semver","status":"affected"},{"version":"1.27.0-0","lessThan":"1.27.2","versionType":"semver","status":"affected"}]}]}],"metrics":{"cvssMetricV31":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","cvssData":{"version":"3.1","vectorString":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","baseScore":9.8,"baseSeverity":"CRITICAL","attackVector":"NETWORK","attackComplexity":"LOW","privilegesRequired":"NONE","userInteraction":"NONE","scope":"UNCHANGED","confidentialityImpact":"HIGH","integrityImpact":"HIGH","availabilityImpact":"HIGH"},"exploitabilityScore":3.9,"impactScore":5.9}],"ssvcV203":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","ssvcData":{"timestamp":"2026-10-09T15:35:58.663117Z","id":"CVE-2026-56857","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}]},"weaknesses":[{"source":"134c704f-9b21-4f2e-91b3-4a467353bcc0","type":"Secondary","description":[{"lang":"en","value":"CWE-1386"}]}],"references":[{"url":"https://go.dev/cl/847305","source":"security@golang.org"},{"url":"https://go.dev/issue/81739","source":"security@golang.org"},{"url":"https://groups.google.com/g/golang-announce/c/U2fTuyDJznI","source":"security@golang.org"},{"url":"https://pkg.go.dev/vuln/GO-2026-6604","source":"security@golang.org"}]}