CVE-2025-21900: linux kernel vulnerability

What is known

In the Linux kernel, the following vulnerability has been resolved: NFSv4: Fix a deadlock when recovering state on a sillyrenamed file If the file is sillyrenamed, and slated for delete on close, it is possible for a server reboot to triggeer an open reclaim, with can again race with the application call to close(). When that happens, the call to put_nfs_open_context() can trigger a synchronous delegreturn call which deadlocks because it is not marked as privileged. Instead, ensure that the call to nfs4_inode_return_delegation_on_close() catches the delegreturn, and schedules it asynchronously.

Business impact

Successful exploitation of CVE-2025-21900, a high vulnerability (CVSS 7.5) affecting linux kernel, may affect the confidentiality, integrity or availability of the vulnerable environment. The exact impact depends on the installed version, exposed interfaces and deployment configuration.

Recommended administrator action

Confirm whether linux kernel is present and compare installed versions with the vendor advisory and NVD record. Apply the vendor patch or documented mitigation; until remediation is complete, reduce exposure of affected interfaces, review relevant logs and monitor for indicators of exploitation. DataHouse can support version verification, managed patching, network exposure reduction, log review and backup validation for dedicated, cloud and colocated environments.

Sources

• NVD
• Reference
• Reference
• Reference