CVE-2025-68775
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk37th percentile - higher than 37% of all known CVEs
Summary
In the Linux kernel net/handshake, duplicate handshake cancellations cause a socket leak. When a second cancellation arrives, remove_pending() returns false, but the socket reference count is still decremented, leading to underflow.
Risk Assessment
This could lead to socket resource exhaustion, causing denial of service (DoS) or system instability.
Recommendation
Apply the patch that adds test_and_set_bit for HANDSHAKE_F_REQ_COMPLETED in the cancel path to detect duplicate cancellations.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: net/handshake: duplicate handshake cancellations leak socket When a handshake request is cancelled it is removed from the handshake_net->hn_requests list, but it is still present in the handshake_rhashtbl until it is destroyed. If a second cancellation request arrives for the same handshake request, then remove_pending() will return false... and assuming HANDSHAKE_F_REQ_COMPLETED isn't set in req->hr_flags, we'll continue processing through the out_true label, where we put another reference on the sock and a refcount underflow occurs. This can happen for example if a handshake times out - particularly if the SUNRPC client sends the AUTH_TLS probe to the server but doesn't follow it up with the ClientHello due to a problem with tlshd. When the timeout is hit on the server, the server will send a FIN, which triggers a cancellation request via xs_reset_transport(). When the timeout is hit on the client, another cancellation request happens via xs_tls_handshake_sync(). Add a test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED) in the pending cancel path so duplicate cancels can be detected.