Use-after-free in Linux kernel - CVE-2026-89689
Published: September 12, 2026
Vulnerability identifier: #VU149123
CSH Severity: Medium
CVSS v4: 6.3 [CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:L/SC:N/SI:N/SA:N]
CVE-ID: CVE-2026-89689
CWE-ID: CWE-416
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vulnerability details
The vulnerability allows a remote attacker to cause memory corruption.
The vulnerability exists due to a use-after-free in nfsd4_sequence() when processing an NFSv4 SEQUENCE request during session slot reduction. A remote attacker can use a high-numbered session slot while acknowledging the slot reduction to cause memory corruption.
Active high-numbered slots can also be freed while in use by concurrent requests.
Affected software
Linux kernel
How to mitigate CVE-2026-89689
Install security update from vendor's repository.