CVE-2026-64400ksmbd: prevent path traversal bypass by restricting caseless retry
Updated under an hour ago ()
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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. When a crafted path attempts to escape the share boundary using parent-directory components ('..'), vfs_path_parent_lookup() detects this and immediately fails, returning -EXDEV. However, a bug exists in __ksmbd_vfs_kern_path() under caseless mode. The function fails to intercept the -EXDEV error and erroneously falls through to the caseless retry logic, which is intended only for genuinely missing files. During this retry process, the path is reconstructed, leading to an unintended LOOKUP_BENEATH bypass that allows write-capable users to create zero-length files or directories outside the exported share. Fix this by ensuring that the execution only proceeds to the caseless lookup retry when the error is specifically -ENOENT. Any other errors, such as -EXDEV from a path traversal attempt, must be returned immediately.
- CVSS
- 8.6 HIGH (v3.1, CNA)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H
- Weakness (CWE)
- Not given
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- Linux
- NVD analysis
- Modified
- Record last updated
- Oct 15, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
Linux Linux linux:linux (from the name) | from 74d7970febf7e9005375aeda0df821d2edffc9f7 before cfb5a56c218888f9d74165dff0c282cd0be97983; 74d7970febf7e9005375aeda0df821d2edffc9f7 builds before 8c9a4f1327eb71efbf14842e7b8a6d965077eb67; 74d7970febf7e9005375aeda0df821d2edffc9f7 builds before 54bab9ba5a9f156ffa9324fcbe5a356fd0242f95; 019aae488dbc67c97a33db03652e20e2c9e3afa7; 6927ffe7479c72e7ebf885507227266a75f7c97d; ef6cc1c465786b3e4e735d1ab8b616b3e94402df; from 5.15.145 before 5.16; from 6.1.71 before 6.2; and 1 more ranges | CNA record |
linux linux_kernel linux:linux_kernel | from 5.15.145 before 5.16; from 6.1.71 before 6.2; from 6.3.10 before 7.1.4 | NVD |
References
- https://git.kernel.org/stable/c/cfb5a56c218888f9d74165dff0c282cd0be97983
- https://git.kernel.org/stable/c/8c9a4f1327eb71efbf14842e7b8a6d965077eb67patch
- https://git.kernel.org/stable/c/54bab9ba5a9f156ffa9324fcbe5a356fd0242f95patch
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.