The ksmbd component in the Linux kernel performed MAC comparisons using memcmp, which depends on data values and therefore leaks timing information. An attacker able to measure the timing of these comparisons can reconstruct the correct MAC bit by bit. Once the MAC is obtained, the attacker can authenticate to the SMB service without legitimate credentials, potentially gaining unauthorized access and exposing data.

All Linux kernel builds that contain ksmbd before the patch replacing memcmp with crypto_memneq. This includes every Linux distribution kernel that has not yet applied the fix; specific version numbers are not provided, so any kernel containing the vulnerable code is considered affected.

The CVSS score of 7.4 indicates moderate‑to‑high severity. An EPSS rating of less than 1% suggests low likelihood of exploitation, and the vulnerability is not listed in the CISA KEV catalog. However, the attack requires network access to the SMB service and accurate timing measurements, which may limit practicality but still poses a risk for systems exposed to untrusted networks.