The Linux kernel’s CIFS implementation holds a read lock while waiting for a lease break acknowledgement, causing a 35‑second timeout when a conflicting open arrives. This race condition prevents the lease break from being acknowledged promptly, resulting in prolonged blocking for client operations and no direct code execution is possible. The kernel code uses the lock to protect shared structures, but the waiting thread blocks other threads from completing the lease break, producing a denial‑of‑service effect for SMB clients that rely on fast lease management. The flaw also manifests as uncontrolled use of wait‑for‑acknowledgement leading to a potential deadlock and resource handling errors (CWE‑833).

This issue affects the Linux kernel on all vendor distributions that ship the CIFS SMB client (cifs.ko). No specific kernel version is listed in the data, so any system that uses the default CIFS driver before the applied patch may be impacted.

The CVSS score of 4.3 indicates a low to moderate severity. The EPSS score is < 1%, showing a very low probability of exploitation, and the vulnerability is not listed in CISA KEV. Nevertheless, the 35‑second wait can be triggered by normal SMB traffic if a lease conflict occurs, leading to performance degradation or temporary denial of service. The issue is a race condition that could be aggravated by high load or scripted lease break requests, but it does not grant remote code execution or privilege escalation.