CVE-2026-72221
CriticalCVSS 9.8Exploitation Probability (EPSS)
Low risk10th percentile - higher than 10% of all known CVEs
Summary
In the Linux kernel, a race condition in the sunrpc module during TLS handshake cancellation was fixed. When wait_for_completion_interruptible_timeout() returns timeout or signal and cancellation loses the race, the handshake callback may not have committed its side effects, leading to double invocation of the handshake or connection teardown despite successful handshake. The fix waits for the callback to commit before checking flags.
Risk Assessment
The vulnerability may cause corruption of the swait_queue structure or termination of valid TLS sessions, potentially leading to system crashes or disruption of network services using RPC/SUNRPC.
Recommendation
It is recommended to urgently update the Linux kernel to a version containing the fix (the commit addressing this issue). Monitor distribution security advisories and apply relevant patches.
Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: sunrpc: wait for in-flight TLS handshake callback when cancel loses race When wait_for_completion_interruptible_timeout() in svc_tcp_handshake() returns 0 (timeout) or -ERESTARTSYS (signal) and tls_handshake_cancel() then returns false, handshake_complete() has won the cancellation race: it has set HANDSHAKE_F_REQ_COMPLETED and is about to invoke svc_tcp_handshake_done(), but the callback's side effects on xpt_flags and on svsk->sk_handshake_done have not yet committed. The current code reads xpt_flags immediately to decide whether the session succeeded. Two races result. If the callback has executed set_bit(XPT_TLS_SESSION) but not yet clear_bit(XPT_HANDSHAKE), svc_tcp_handshake() sees a session, enqueues the transport, and returns. svc_xprt_received() then clears XPT_BUSY, a worker thread picks the transport up, the dispatcher in svc_handle_xprt() observes XPT_HANDSHAKE still set, and xpo_handshake is invoked a second time. That svc_tcp_handshake() calls init_completion(&svsk->sk_handshake_done) while the original callback concurrently calls complete_all() on it, corrupting the embedded swait_queue. If the callback has set HANDSHAKE_F_REQ_COMPLETED but not yet entered svc_tcp_handshake_done(), svc_tcp_handshake() reads XPT_TLS_SESSION as clear and tears the connection down even though the handshake is about to succeed. Wait for the callback to commit before inspecting xpt_flags. The completion is guaranteed to fire because handshake_complete() invokes svc_tcp_handshake_done() unconditionally once it has set HANDSHAKE_F_REQ_COMPLETED.