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CVE PROGRAM SOURCE RECORD8.6 High

CVE-2026-64400

ksmbd: prevent path traversal bypass by restricting caseless retry

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Status
Published
Published
Updated
Assigning organization
Linux

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

Version statuses are supplied by the assigning organization. Consult the original record for detailed ranges and platform conditions.

Linux Linux

Default version status: unaffected

  • 6927ffe7479c72e7ebf885507227266a75f7c97d to < 21f050439db157f2afcc19885dec14549ca6ffc0affected
  • 74d7970febf7e9005375aeda0df821d2edffc9f7 to < eec1dd2586c4016b7555a5d047db2b3756459fb2affected
  • 74d7970febf7e9005375aeda0df821d2edffc9f7 to < a1c331d98313380c38f616c8b28b890ec8ef9c28affected
  • 74d7970febf7e9005375aeda0df821d2edffc9f7 to < cfb5a56c218888f9d74165dff0c282cd0be97983affected
  • 74d7970febf7e9005375aeda0df821d2edffc9f7 to < 8c9a4f1327eb71efbf14842e7b8a6d965077eb67affected
  • 74d7970febf7e9005375aeda0df821d2edffc9f7 to < 54bab9ba5a9f156ffa9324fcbe5a356fd0242f95affected
  • 019aae488dbc67c97a33db03652e20e2c9e3afa7affected
  • ef6cc1c465786b3e4e735d1ab8b616b3e94402dfaffected
  • 6.1.71 to < 6.1.191affected
  • 5.15.145 to < 5.16affected
  • 6.3.10 to < 6.4affected

Linux Linux

Default version status: affected

  • 6.4affected
  • 0 to < 6.4unaffected
  • 6.1.191 to ≤ 6.1.*unaffected
  • 6.6.160 to ≤ 6.6.*unaffected
  • 6.12.114 to ≤ 6.12.*unaffected
  • 6.18.57 to ≤ 6.18.*unaffected
  • 7.1.4 to ≤ 7.1.*unaffected
  • 7.2 to ≤ *unaffected

References