Use-after-free in Linux kernel - CVE-2026-89661
Published: September 12, 2026
Vulnerability identifier: #VU149143
CSH Severity: Low
CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89661
CWE-ID: CWE-416
Exploitation vector: Local access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a local privileged user to cause a denial of service.
The vulnerability exists due to a use-after-free in nfsd4_cancel_copy_by_sb() when processing a filesystem path written to /proc/fs/nfsd/unlock_filesystem after NFS server shutdown. A local privileged user can stop the NFS server and write a filesystem path to the endpoint to cause a denial of service.
Affected software
Linux kernel
How to mitigate CVE-2026-89661
Install security update from vendor's repository.