fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath

Summary

In the Linux kernel, the following vulnerability has been resolved: fs/smb/client: fix out-of-bounds read in cifs_sanitize_prepath When cifs_sanitize_prepath is called with an empty string or a string containing only delimiters (e.g., "/"), the current logic attempts to check *(cursor2 - 1) before cursor2 has advanced. This results in an out-of-bounds read. This patch adds an early exit check after stripping prepended delimiters. If no path content remains, the function returns NULL. The bug was identified via manual audit and verified using a standalone test case compiled with AddressSanitizer, which triggered a SEGV on affected inputs.

Timeline

1. May 6, 2026, 7:40 AM UTCCVE published
2. Oct 16, 2026, 3:14 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Oct 19, 2026, 7:06 PM UTCRecord last updated

Affected versions

• Linux Linux

  From c63433a09d6ae4c226fcbc66da4c58fc189fd746 · fixed in a2ba20c17de8eb028f96b1d85f119d3d25655bd9; From a31080899d5fdafcccf7f39dd214a814a2c82626 · fixed in fbced33599653471b4581dfe1abc7b467031f126; From a31080899d5fdafcccf7f39dd214a814a2c82626 · fixed in 5d4fe469fe7dbff7d874c196bb680a82f2625d95; From a31080899d5fdafcccf7f39dd214a814a2c82626 · fixed in 2d29214448ec0f4e7e18bb1c14dd4a6c07f1c439; From a31080899d5fdafcccf7f39dd214a814a2c82626 · fixed in 86f9c23e0814cfdffda9eedf0c591c51ba209010; From a31080899d5fdafcccf7f39dd214a814a2c82626 · fixed in 49b1ce6d7cfb6c5a49f68bf5ccfcfb6ba14e63c3; From a31080899d5fdafcccf7f39dd214a814a2c82626 · fixed in 78ec5bf2f589ec7fd8f169394bfeca541b077317; From 5.15.11 · fixed in 5.15.209

• Linux Linux

  5.16

• KernelLinux

  fixed in 5.15.209; From 5.16.0 · fixed in 6.1.175; fixed in 6.6.136; From 6.2.0 · fixed in 6.12.83; From 6.7.0 · fixed in 6.18.24; From 6.13.0 · fixed in 6.19.14

References 7