CVE-2026-64400

CVE CVE-2026-64400EUVD EUVD-2026-48944Published 2026-07-25T08:50:43.000ZLast changed 2026-08-05T12:41:38.000ZCVSS 8.6

What the advisory describes

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.

Source: EUVD (ENISA), in the words of the advisory.

Products the advisory names

These come from the advisory itself, not from any check we performed.

Linux — Linux patch: 0; 5.15.145 <5.16; 6.4; 6927ffe7479c72e7ebf885507227266a75f7c97d; 6.3.10 <6.4; patch: 7.2-rc1; patch: 7.1.4; 019aae488dbc67c97a33db03652e20e2c9e3afa7; 6.1.71 <6.2; 74d7970febf7e9005375aeda0df821d2edffc9f7 <54bab9ba5a9f156ffa9324fcbe5a356fd0242f95; ef6cc1c465786b3e4e735d1ab8b616b3e94402df; 74d7970febf7e9005375aeda0df821d2edffc9f7 <8c9a4f1327eb71efbf14842e7b8a6d965077eb67

The versions shown are the advisory's own. Patchlage compares no version numbers and derives no judgement from them — which version is installed is something a person has to look up.

Carried in the product catalogue

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Linux — Linux

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