ksmbd: validate ACE size against SID sub-authorities

Summary

In the Linux kernel, the following vulnerability has been resolved: ksmbd: validate ACE size against SID sub-authorities set_ntacl_dacl() validates sid.num_subauth before copying an ACE, but does not verify that the declared ACE size contains all sub-authorities described by that field. An undersized ACE can therefore be copied and later make the POSIX ACL deduplication walk inspect data beyond the copied ACE boundary. The existing initial bound check is also too small. It only ensures that the ACE size field is accessible before set_ntacl_dacl() reads sid.num_subauth farther into the input buffer. Require enough input for the fixed SID header before accessing num_subauth, reject ACEs smaller than that header, and skip ACEs whose declared size cannot contain the complete SID. This makes the validation consistent with the other ACE walk paths.

Timeline

1. Aug 10, 2026, 11:58 AM UTCCVE published
2. Oct 3, 2026, 10:55 AM UTCRecord last updated

Affected versions

• Linux Linux

  From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 5a2d9fe0e87c71baa0aaa1cfc1361892fcd1ece0; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in b7cb5bf0855470799f12da825de91e48951b3876; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 62d80d7c2d9428085e7458ad4c06ca8c0984039b; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 337022d9dfac441c3b35e4455a51aa981996e02e; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 61fd3559199f7fa693dcbff35e59477e24af041a; From e2f34481b24db2fd634b5edb0a5bd0e4d38cc6e9 · fixed in 5152c6d49e3fd4e9f2e857c57527aead752f1f87

• Linux Linux

  5.15

• KernelLinux

  From 5.15.0 · fixed in 6.1.189; From 6.2.0 · fixed in 6.6.148; From 6.7.0 · fixed in 6.12.101; From 6.13.0 · fixed in 6.18.42; From 6.19.0 · fixed in 7.1.6

References 6