High [CVE-2026-64597] fix double-free in SMB2_close replay
This high-severity Red Hat Linux advisory covers CVE-2026-64597 affecting Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 9, Red Hat Enterprise Linux for NVIDIA 26.
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Summary
In the Linux kernel, the following vulnerability has been resolved: smb: client: fix double-free in SMB2_close() replay A response-bearing attempt can return a replayable error and free its response buffer. If SMB2_close_init() fails before the next send, cleanup retains the previous buffer type and frees that response again.
Reset response bookkeeping before each attempt to prevent the stale free. This double-free condition can lead to memory corruption, potentially resulting in a denial of service or the execution of arbitrary code.
A double-free vulnerability exists in the SMB2_close() replay mechanism where a response buffer's bookkeeping state can become stale across retry attempts, leading to the same buffer being freed twice. This could result in memory corruption, potentially causing a denial of service (kernel panic) or other undefined behavior.
Exploitation requires the victim system to connect to a malicious or compromised SMB server. Red Hat severity: Important — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).
Weakness: CWE-415. Affected Red Hat products: Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 9; Red Hat Enterprise Linux for NVIDIA 26.
Under investigation: Red Hat OpenShift Container Platform 4. Red Hat lists Red Hat Enterprise Linux 10; Red Hat Enterprise Linux 6; Red Hat Enterprise Linux 7; Red Hat Enterprise Linux 8 as not affected.
Affected versions
No affected-version range was extracted from the source record. The vendor advisory is authoritative — check it before change work.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Fixed versions
No fixed release is recorded yet. That does not prove no patch exists — confirm against the vendor advisory.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
Mitigation checklist
- If SMB/CIFS client functionality is not required, the 'cifs' kernel module can be blocklisted to prevent it from loading. Systems that do not mount SMB/CIFS shares are not affected. For systems that require SMB client access, ensure connections are only made to trusted SMB servers.
Official advisory · high-confidence parse· fetched 1 hour ago·verify at source
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