CVE-2026-43350

Summary

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.

Affected Software

VendorProductVersion RangeStatus
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < 23b54d6cc3ef30a51d984dc74364f24039ae2ecbaffected
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < 1592a6cd6f653f2d24572a6976c7a775b19f4940affected
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < 8bd4cad3f458d11650d51c2d24b03fb1770ae6ccaffected
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < b53b8e98c23310294fc45fc686db5ee860311896affected
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < c8eef12af1cc73031639ea7cf16e0b10e2536b0baffected
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < 38a69f08ee82c450d3e4168707fff2e317dc3ff7affected
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < f8488c07bea2431ee12a6067d736578064fa46b4affected
LinuxLinuxe2f8fbfb8d09c06decde162090fac3ee220aa280 < 2757ad3e4b6f9e0fed4c7739594e702abc5cab21affected
LinuxLinux5.4affected
LinuxLinux0 < 5.4unaffected
LinuxLinux5.10.259 <= 5.10.*unaffected
LinuxLinux5.15.210 <= 5.15.*unaffected
LinuxLinux6.1.175 <= 6.1.*unaffected
LinuxLinux6.6.136 <= 6.6.*unaffected
LinuxLinux6.12.84 <= 6.12.*unaffected
LinuxLinux6.18.25 <= 6.18.*unaffected
LinuxLinux7.0.2 <= 7.0.*unaffected
LinuxLinux7.1 <= *unaffected

Weaknesses

References