Description
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.
Affected products
linux: linux kernel
References6
- git.kernel.org/stable/c/54bab9ba5a9f156ffa9324fcbe5a356fd0242f95 Patch
- git.kernel.org/stable/c/8c9a4f1327eb71efbf14842e7b8a6d965077eb67 Patch
- git.kernel.org/stable/c/21f050439db157f2afcc19885dec14549ca6ffc0
- git.kernel.org/stable/c/a1c331d98313380c38f616c8b28b890ec8ef9c28
- git.kernel.org/stable/c/cfb5a56c218888f9d74165dff0c282cd0be97983
- git.kernel.org/stable/c/eec1dd2586c4016b7555a5d047db2b3756459fb2
Metrics
- CVSS 3.1
-
8.6
HIGH
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H - EPSS — exploit probability
- 0% percentile: 39 · as of 14 November 2026
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