CVE-2026-89709

A flaw was found in the Linux kernel's lockd and nfsd components. An unguarded dereference of nlmsvc_ops after the nfsd module is removed can lead to a NULL pointer dereference or a use-after-free condition. This vulnerability could allow a local attacker to cause a denial of service.

A race in lockd and nfsd callback dispatch can leave nlmsvc_ops pointing to nfsd data and callback functions after the nfsd module is unloaded. A remote NLM client may exercise the affected dispatch paths while a local administrator unloads nfsd, resulting in a NULL pointer dereference or a use after free of unloaded module data or module text. For the CVSS the PR:N is used for the paranoid score because the remote client does not need local code execution or an account on the target. Reliable triggering still requires the high complexity race with concurrent nfsd module unload. The base impact is denial of service. Exposure requires lockd and NLM RPC to be reachable and nfsd to be unloadable as a module. These services are commonly limited to trusted storage networks but may be reachable by internal network clients.

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.

Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base or stability.