CVE-2026-89692

A flaw was found in the Linux kernel's Network File System (NFS) daemon, nfsd. This vulnerability occurs when a delegation recall operation fails, leaving a critical internal flag uncleared. This prevents subsequent attempts to break the same delegation, leading to a denial of service where file operations or locks can stall indefinitely. This can disrupt access to shared network resources.

MODERATE impact. A flaw was found in the Linux kernel's Network File System daemon (nfsd) in Red Hat Enterprise Linux 10.2 and OpenShift Container Platform 5.0/5.1. When the NFS server needs to break a delegation, nfsd_break_one_deleg() sets the NFSD4_CALLBACK_RUNNING flag to serialize recall work and queues the recall; if queueing the recall fails, the flag is left permanently set because the only code path that clears it runs from the workqueue that was never queued. Every subsequent attempt to break that same delegation then silently returns without performing the recall, so a conflicting open or lock request on the delegated file stalls indefinitely, resulting in a denial of service against shared NFS resources. Triggering the flaw requires an active NFS delegation plus a failed recall queue attempt on the server, which is why Red Hat rates it moderate (CVSS 5.5, local attack vector with privileges required) rather than the upstream important rating of 7.5, which assumes an unauthenticated network attacker. Earlier Red Hat Enterprise Linux and OpenShift streams are not affected because the vulnerable code, introduced upstream in kernel 6.15, is not present in those kernels. For the affected streams the fix is currently deferred; the residual risk is confined to NFS servers that grant delegations, where a failed recall can leave client file operations or locks blocked until the delegation state is cleared.

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 do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.