CVE-2026-52911
HighCVSS 8.8Exploitation Probability (EPSS)
Low risk28th percentile - higher than 28% of all known CVEs
Summary
In the Linux kernel, a vulnerability in ksmbd was found where the conn->binding flag remained set after SESSION_SETUP, allowing global session lookup for connections not bound to that session. The fix tightens the global lookup to require the session to have the connection registered in its channel xarray.
Risk Assessment
The organization is at risk of unauthorized access to SMB sessions by connections that have not been formally bound, potentially leading to privilege escalation or data integrity compromise.
Recommendation
Immediately update the Linux kernel to a version containing the fix (commit in the ksmbd repository) and apply the security patch from your system distributor.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ksmbd: scope conn->binding slowpath to bound sessions only When the binding SESSION_SETUP sets conn->binding = true, the flag stays set after the call so that the global session lookup in ksmbd_session_lookup_all() can find the session, which was not added to conn->sessions. Because the flag is connection-wide, the global lookup path will also resolve any other session by id if asked. Tighten the global lookup so that the returned session must have this connection registered in its channel xarray (sess->ksmbd_chann_list). The channel entry is installed by the existing binding_session path in ntlm_authenticate()/krb5_authenticate() when a SESSION_SETUP completes successfully, so this condition is a strict equivalent of "this connection has been accepted as a channel of this session". Connections that have not bound to a given session cannot reach it via the global table. The existing conn->binding gate for entering the slowpath is preserved so that non-binding connections keep the fast-path-only behavior, and the session->state check is unchanged.