CVE-2026-64597 smb: client: fix double-free in SMB2_close() replay
A double-free vulnerability in the Linux kernel SMB client allows attackers to cause denial of service or potentially execute code via crafted SMB2 close operations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64597?
CVE-2026-64597 is a critical use after free vulnerability in Linux, published on 6 Aug 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
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.
Weakness: CWE-415
Which versions are affected by CVE-2026-64597?
How do I fix CVE-2026-64597?
Apply the vendor's patch.
Upgrade to the fixed version. These bugs are found with fuzzing and sanitisers and avoided by memory-safe languages. More about Use after free.
Is CVE-2026-64597 being exploited?
There is no known exploitation of CVE-2026-64597 in the wild and no public exploit code.
Sources
Also known as BELL-CVE-2026-64597, DEBIAN-CVE-2026-64597, GHSA-4vgx-hp6g-jmm8, UBUNTU-CVE-2026-64597.