CVE-2026-89706

Name of the Vulnerable Software and Affected Versions Linux kernel (affected versions not specified)

Description An issue exists in the nfsd component where the write verifier is not rotated when an asynchronous COPY writeback fails. During an async COPY operation, the system captures the nn->writeverf variable and reports it to the client via CB OFFLOAD. If the vfs fsync range() or filemap check wb err() functions within nfsd copy file range() report an error, the server fails to rotate the write verifier. Consequently, when a client receives an NFS UNSTABLE status and issues a COMMIT to ensure data durability, the server returns the unchanged verifier. This leads the client to incorrectly assume the copy is durable, resulting in the silent loss of data that failed writeback.

Recommendations At the moment, there is no information about a newer version that contains a fix for this vulnerability.