CVE-2024-50043
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk12th percentile - higher than 12% of all known CVEs
Summary
In the Linux kernel, the NFS server (nfsd) has an issue in FREE_STATEID handling. Sending multiple FREE_STATEIDs for the same delegation stateid can lead to use-after-free or counter refcount underflow. The fix addresses the critical section in nfsd4_free_stateid() where the lock is dropped before calling nfs4_put_stid(), allowing the stateid to be found again.
Risk Assessment
An attacker could exploit this vulnerability to cause a system crash or potentially escalate privileges in kernel context.
Recommendation
Update the Linux kernel to a patched version. Also monitor for similar issues in other code paths.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: nfsd: fix possible badness in FREE_STATEID When multiple FREE_STATEIDs are sent for the same delegation stateid, it can lead to a possible either use-after-free or counter refcount underflow errors. In nfsd4_free_stateid() under the client lock we find a delegation stateid, however the code drops the lock before calling nfs4_put_stid(), that allows another FREE_STATE to find the stateid again. The first one will proceed to then free the stateid which leads to either use-after-free or decrementing already zeroed counter.