CVE-2026-89689

A flaw was found in the Linux kernel's Network File System (NFS) daemon, nfsd. A remote attacker could exploit a use-after-free vulnerability in the nfsd4_sequence() function. This occurs when the system attempts to reduce the number of active session slots while a client is still using one of the slots being freed. Successful exploitation leads to memory corruption, which can result in a denial of service or other system instability.

This vulnerability is rated as Important severity because an NFSv4 client can trigger kernel memory corruption and cause a system crash or arbitrary code execution within the kernel context. The flaw only impacts hosts running an NFS server, which is not enabled by default on standard Red Hat Enterprise Linux installations. Systems that do not export file shares over NFS or that restrict access to trusted clients are not exposed.

The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.