SB20260425100 - Memory leak in Linux kernel smb server

Description

This security bulletin contains information about 1 vulnerability.

1) Memory leak (CVE-ID: CVE-2026-31610)

CWE-ID: CWE-401 - Missing release of memory after effective lifetime

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

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

The vulnerability exists due to a memory leak in smb2_sess_setup() SPNEGO negotiation handling when processing a malformed SPNEGO negotiation token. A remote attacker can send a specially crafted negotiation blob to cause a denial of service.

The issue is reachable pre-authentication, and malformed later elements in the same token can leave an allocated mechToken uncleared after both SPNEGO grammars fail.

Remediation

Install update from vendor's website.

References

• https://git.kernel.org/stable/c/269c800a7a7e363459291885b35f7bc72e231ed6
• https://git.kernel.org/stable/c/6c8c44e6553b9f072f62d9875e567766eb293162
• https://git.kernel.org/stable/c/dd53414e301beb915fe672dc4c4a51bafb917604
• https://git.kernel.org/stable/c/dd577cb55588ec3fbc66af3621280306601c4192