CVE-2026-43350

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: require a full NFS mode SID before reading mode bits parse_dacl() treats an ACE SID matching sid_unix_NFS_mode as an NFS mode SID and reads sid.sub_auth[2] to recover the mode bits. That assumes the ACE carries three subauthorities, but compare_sids() only compares min(a, b) subauthorities. A malicious server can return an ACE with num_subauth = 2 and sub_auth[] = {88, 3}, which still matches sid_unix_NFS_mode and then drives the sub_auth[2] read four bytes past the end of the ACE. Require num_subauth >= 3 before treating the ACE as an NFS mode SID. This keeps the fix local to the special-SID mode path without changing compare_sids() semantics for the rest of cifsacl.

References

• https://git.kernel.org/stable/c/2757ad3e4b6f9e0fed4c7739594e702abc5cab21
• https://git.kernel.org/stable/c/38a69f08ee82c450d3e4168707fff2e317dc3ff7
• https://git.kernel.org/stable/c/b53b8e98c23310294fc45fc686db5ee860311896
• https://git.kernel.org/stable/c/c8eef12af1cc73031639ea7cf16e0b10e2536b0b
• https://git.kernel.org/stable/c/f8488c07bea2431ee12a6067d736578064fa46b4