Use-after-free in Linux kernel - CVE-2026-89641
Published: September 12, 2026
Vulnerability identifier: #VU149170
CSH Severity: Low
CVSS v4: 0 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:N/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89641
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local user to trigger a use-after-free.
The vulnerability exists due to use-after-free in the CIFS client's cifs_file_set_size() function when falling back to path-based file-size operations after a failed handle-based set_file_size() RPC. A local user can cause the fallback to reuse a freed tcon to trigger a use-after-free.
Exploitation requires a tlink to be removed during reconnection or session teardown and its last reference to be released.
Affected software
Linux kernel
How to mitigate CVE-2026-89641
Install security update from vendor's repository.