Use-after-free in Linux kernel - CVE-2026-64401
Published: July 27, 2026
Vulnerability identifier: #VU139571
CSH Severity: Low
CVSS v4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-64401
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to cause a denial of service.
The vulnerability exists due to a use-after-free in the SMB client witness notification handling in fs/smb/client/cifs_swn.c when processing witness notifications for shared registrations. A local user can trigger notification handling involving a freed tcon pointer to cause a denial of service.
Exploitation requires a same-share second mount so that a registration remains live after the first tcon is unregistered and freed.
Affected software
Linux kernel
Debian Linux
linux (Debian package)
Debian Linux
linux (Debian package)
How to mitigate CVE-2026-64401
Install security update from vendor's repository.
Linux kernel - update to 7.0 rc3
linux (Debian package) - update to 6.12.100-1
linux (Debian package) - update to 6.12.100-1
External References
- https://git.kernel.org/stable/c/0700f946659d0ab2352ec8a9b1c6fc74b13a27d7
- https://git.kernel.org/stable/c/51d18db392e5386a7bb9e816d611f14e600cca3c
- https://git.kernel.org/stable/c/91b8a58c6ac15c7db6518f696389933282f88da7
- https://git.kernel.org/stable/c/945b4a4a54497db1dcb2f20ef801a84e884dac21
- https://git.kernel.org/stable/c/aa3c0cab4b28c5007ec570c63e1d6ad6943ed0fd
- https://git.kernel.org/stable/c/ec457f9afe5ae9538bdcd58fd4cb442b9787e183