The vulnerability is a resource exhaustion flaw in the Linux kernel’s SMB server (ksmbd), identified as CWE-911 and CWE-401. When a transport allocation fails during a new connection, the active connection counter is incremented but never decremented, causing that slot to be permanently lost. Repeated failures eventually exhaust the connection pool, after which every subsequent connection, including legitimate ones, is rejected with a “Limit the maximum number of connections” error, leading to a denial‑of‑service of the SMB service until the kernel module is reloaded or the system rebooted.

All Linux systems that contain the ksmbd SMB server component in the kernel are affected. No specific kernel version range is listed, so any kernel build that lacks the commit that fixes the active_num_conn leak is vulnerable.

The CVSS score of 7.5 indicates a medium‑to‑high severity flaw. An unauthenticated attacker can trigger the vulnerability by opening TCP connections to port 445 and sending large packets that force allocation failures. The flaw leads to a permanent resource leak that exhausts the connection pool, after which legitimate connections are refused until the ksmbd module is reloaded or the system is rebooted, effectively denying SMB service. Although exploitation is technically possible, the EPSS score of < 1% indicates that in practice this vulnerability is likely to be exploited rarely; the issue is not listed in CISA KEV.