CVE-2026-64597: smb: client: fix double-free in SMB2_close() replay

CSIRTS triage

What

A double-free vulnerability exists in SMB2_close() during replay handling in the SMB client code.

Who is affected

Systems running affected Linux kernel versions with SMB2 client support are affected.

Urgency

High; CVSS 8.6 indicates significant risk; remediation should be prioritized.

Action

Update to a Linux kernel version that fixes the double-free in SMB2_close() replay handling.

AI-assisted analysis generated from the source advisory — verify against the original.

Details

Source

Microsoft Security Response Center (INTL · vendor-psirt · site)

Severity

high — CVSS 8.6

Published

2026-08-11

Exploitation

Not in CISA KEV at last sync

Original advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-64597

Exploitation outlook

EPSS (FIRST.org) estimates each CVE’s probability of exploitation in the next 30 days — here is the CSIRTS.com read on those numbers.

• Low exploitation riskCVE-2026-645970.36% 30-day exploitation probability — currently an unlikely target, but scores change as exploit code circulates. Riskier than 29% of all EPSS-scored CVEs.

Referenced CVEs

Same CVEs, other sources

How other CERTs, PSIRTs and databases cover the vulnerabilities in this advisory.

• medium[NEW] [medium] Linux Kernel: Multiple Vulnerabilitiescert-bund
• criticalCVE-2026-64597: In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-fr…nvd

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