CVE-2025-21795

MediumCVSS 5.5

Published: 27/02/2025(UTC)Updated: 14/07/2026(UTC)Translated: 16/07/2026(UTC)NVD NIST

Exploitation Probability (EPSS)

Low risk

0.22%

13th percentile - higher than 13% of all known CVEs

Summary

A vulnerability in the Linux kernel causes a hang in nfsd4_shutdown_callback when an NFS client is in courtesy state, blocking for up to 15 minutes until TCP drops the connection.

Risk Assessment

The hang may render NFS services unavailable for up to 15 minutes, impacting applications relying on file sharing.

Recommendation

Apply the latest Linux kernel patch that modifies nfsd4_run_cb_work to skip RPC calls for courtesy-state clients.

Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: NFSD: fix hang in nfsd4_shutdown_callback If nfs4_client is in courtesy state then there is no point to send the callback. This causes nfsd4_shutdown_callback to hang since cl_cb_inflight is not 0. This hang lasts about 15 minutes until TCP notifies NFSD that the connection was dropped. This patch modifies nfsd4_run_cb_work to skip the RPC call if nfs4_client is in courtesy state.