CVE-2026-53271

About vulnerability

In the Linux kernel, the following vulnerability has been resolved: ksmbd: fix NULL-deref of opinfo->conn in oplock/lease break notifiers smb2_oplock_break_noti() and smb2_lease_break_noti() read opinfo->conn into a local with neither READ_ONCE() nor a NULL check. Both run from oplock_break() after opinfo_get_list() has dropped ci->m_lock, so a concurrent SMB2 LOGOFF (session_fd_check()) can set op->conn = NULL under ci->m_lock within that window. ksmbd_conn_r_count_inc(conn) then writes through NULL at offset 0xc4 – a remotely triggerable oops. Guard both reads the way compare_guid_key() already does: read opinfo->conn with READ_ONCE() and return early if it is NULL, before allocating the work struct so nothing leaks. A NULL conn means the client is gone and the break is moot, so return 0; oplock_break() treats that as success and runs the normal teardown. A flaw was found in the ksmbd component of the Linux kernel. A remote attacker could exploit a NULL-dereference vulnerability in the oplock/lease break notifiers. This occurs because opinfo->conn is read without proper checks, allowing a concurrent Server Message Block (SMB2) LOGOFF to set op->conn to NULL. Successful exploitation leads to a kernel oops, resulting in a Denial of Service (DoS).

Live-patch status from KernelCare for each operating system.