CVE-2021-38199

A flaw was found in the hanging of mounts in the Linux kernel's NFS4 subsystem where remote servers are unreachable for the client during migration of data from one server to another (during trunking detection). This flaw allows a remote NFS4 server (if the client is connected) to starve the resources, causing a denial of service. The highest threat from this vulnerability is to system availability.

This flaw is rated as having a Low impact because the known scenario of attack doesn't allow denial of service for the NFS itself, but only potentially does denial of service for some applications that can fail during remount after NFS mounts temporary fail (and both because this kind of attacks like from some network service server to the client with drop connection or similar doesn't look like something that client not-safe for, and as result this type of attacks should not be considered as sensitive severity impact).

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.

If not using NFS, then to mitigate this issue, prevent the module nfsv4 from being loaded. Please see https://access.redhat.com/solutions/41278 for information on how to blacklist a kernel module to prevent it from loading automatically.