CVE-2026-43350

smb: client: require a full NFS mode SID before reading mode bits

State: Published
Severity: 7.6 High
Published: May 8, 2026
Updated: Oct 19, 2026
Reserved: May 1, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	7.6 High	CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:L/A:H	Linux

Weaknesses

CWE-125 Out-of-bounds Read

Affected Products

Product	Versions
LinuxLinux	e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 23b54d6cc3ef30a51d984dc74364f24039ae2ecbAffected e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 1592a6cd6f653f2d24572a6976c7a775b19f4940Affected e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 8bd4cad3f458d11650d51c2d24b03fb1770ae6ccAffected e2f8fbfb8d09c06decde162090fac3ee220aa280 to before b53b8e98c23310294fc45fc686db5ee860311896Affected e2f8fbfb8d09c06decde162090fac3ee220aa280 to before c8eef12af1cc73031639ea7cf16e0b10e2536b0bAffected e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 38a69f08ee82c450d3e4168707fff2e317dc3ff7Affected e2f8fbfb8d09c06decde162090fac3ee220aa280 to before f8488c07bea2431ee12a6067d736578064fa46b4Affected e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 2757ad3e4b6f9e0fed4c7739594e702abc5cab21Affected
LinuxLinux	5.4Affected before 5.4Not affected 5.10.259 through 5.10.Not affected 5.15.210 through 5.15.Not affected 6.1.175 through 6.1.Not affected 6.6.136 through 6.6.Not affected 6.12.84 through 6.12.Not affected 6.18.25 through 6.18.Not affected 7.0.2 through 7.0.*Not affected 7.1 and laterNot affected

Product

Versions

LinuxLinux

e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 23b54d6cc3ef30a51d984dc74364f24039ae2ecbAffected
e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 1592a6cd6f653f2d24572a6976c7a775b19f4940Affected
e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 8bd4cad3f458d11650d51c2d24b03fb1770ae6ccAffected
e2f8fbfb8d09c06decde162090fac3ee220aa280 to before b53b8e98c23310294fc45fc686db5ee860311896Affected
e2f8fbfb8d09c06decde162090fac3ee220aa280 to before c8eef12af1cc73031639ea7cf16e0b10e2536b0bAffected
e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 38a69f08ee82c450d3e4168707fff2e317dc3ff7Affected
e2f8fbfb8d09c06decde162090fac3ee220aa280 to before f8488c07bea2431ee12a6067d736578064fa46b4Affected
e2f8fbfb8d09c06decde162090fac3ee220aa280 to before 2757ad3e4b6f9e0fed4c7739594e702abc5cab21Affected

LinuxLinux

5.4Affected
before 5.4Not affected
5.10.259 through 5.10.*Not affected
5.15.210 through 5.15.*Not affected
6.1.175 through 6.1.*Not affected
6.6.136 through 6.6.*Not affected
6.12.84 through 6.12.*Not affected
6.18.25 through 6.18.*Not affected
7.0.2 through 7.0.*Not affected
7.1 and laterNot affected

References

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