SB20260502142 - Improper input validation in Linux kernel smb server

Description

This security bulletin contains information about 1 vulnerability.

1) Improper input validation (CVE-ID: CVE-2026-31706)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green

The vulnerability allows a remote user to cause a denial of service.

The vulnerability exists due to improper input validation in smb_inherit_dacl() when processing a tampered parent directory DACL xattr during SMB2 CREATE. A remote user can trigger inheritance of a crafted security.NTACL value to cause a denial of service.

Exploitation requires a parent directory security.NTACL xattr to be tampered while preserving the hash bytes so the xattr check passes.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/063a7409b0de46d7c770b65bb0338e6fdb3b1f0a
• https://git.kernel.org/stable/c/3e4e2ea2a781018ed5d75f969e3e5606beb66e48
• https://git.kernel.org/stable/c/3e5360b422dd741cb315654a191fa73869a37414
• https://git.kernel.org/stable/c/59c32abaaec9cdd6164811c7e864e72f7554b82d