CVE-2026-89664

A flaw was found in the Linux kernel's Network File System Daemon (nfsd). When processing malformed NFSv4 OPEN compound operations that include valid Portable Operating System Interface (POSIX) Access Control List (ACL) attributes, the kernel fails to release allocated memory resources. This oversight can lead to a memory leak, which, over time, could exhaust system memory and result in a Denial of Service (DoS) for affected systems.

NFSD can leak refcounted POSIX ACL objects decoded from NFSv4 OPEN create attributes when a malformed OPEN compound exits through a non seqid mutating error path before nfsd4_open runs, or when a replay encoding path bypasses operation release handling. A remote NFS client that can reach the NFSv4 server and send crafted OPEN compounds with valid POSIX ACL attributes can repeat the condition and gradually consume kernel memory. For the CVSS the PR:N is used because exploitation does not require local code execution or privileges on the target host beyond network reachability to the NFS service. The issue is network reachable over NFS but practical exposure is usually limited to hosts that expose nfsd to trusted internal networks. Impact is denial of service via memory exhaustion, with no evidence of UAF, arbitrary write, information disclosure, or privilege escalation.

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.