{"id":"CVE-2026-64400","url":"https://www.cyber-defence.io/tools/cve/CVE-2026-64400","generatedAt":"2026-10-28T09:27:06.772Z","title":"In the Linux kernel, the following vulnerability has been resolved: ksmbd: prevent path traversal bypass by restricting caseless retry ksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path resolution within the share root.","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nksmbd: prevent path traversal bypass by restricting caseless retry\n\nksmbd_vfs_path_lookup() enforces LOOKUP_BENEATH to restrict path\nresolution within the share root. When a crafted path attempts to\nescape the share boundary using parent-directory components ('..'),\nvfs_path_parent_lookup() detects this and immediately fails,\nreturning -EXDEV.\n\nHowever, a bug exists in __ksmbd_vfs_kern_path() under caseless mode.\nThe function fails to intercept the -EXDEV error and erroneously\nfalls through to the caseless retry logic, which is intended only\nfor genuinely missing files. During this retry process, the path\nis reconstructed, leading to an unintended LOOKUP_BENEATH bypass\nthat allows write-capable users to create zero-length files or\ndirectories outside the exported share.\n\nFix this by ensuring that the execution only proceeds to the caseless\nlookup retry when the error is specifically -ENOENT. Any other errors,\nsuch as -EXDEV from a path traversal attempt, must be returned immediately.","published":"2026-07-25T10:17:24.000Z","lastModified":"2026-10-21T13:19:23.000Z","status":"Modified","sourceIdentifier":"416baaa9-dc9f-4396-8d5f-8c081fb06d67","cvss":{"version":"3.1","score":8.6,"severity":"HIGH","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H"},"cwe":[],"affected":["linux/linux kernel"],"epss":{"score":0.00618,"percentile":0.49382,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.62%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://git.kernel.org/stable/c/54bab9ba5a9f156ffa9324fcbe5a356fd0242f95","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/8c9a4f1327eb71efbf14842e7b8a6d965077eb67","tags":["Patch"],"source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/a1c331d98313380c38f616c8b28b890ec8ef9c28","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/cfb5a56c218888f9d74165dff0c282cd0be97983","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"},{"url":"https://git.kernel.org/stable/c/eec1dd2586c4016b7555a5d047db2b3756459fb2","source":"416baaa9-dc9f-4396-8d5f-8c081fb06d67"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-64400","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}