CVE Catalog

CVE-2026-74692

HighCVSS 7.5
Published: Updated: Translated: NVD NIST

Exploitation Probability (EPSS)

Low risk
0.49%

40th percentile - higher than 40% of all known CVEs

Summary

A TOCTOU race condition was found in the Linux kernel's net/smc module. The smc_listen_out() function checks the socket state without holding the lock, then acquires it later, allowing a race with listener close. This can lead to kernel memory leaks due to unreleased references to the child socket.

Risk Assessment

A remote attacker opening TCP connections while the server calls close() can exhaust kernel memory, causing a denial of service (system crash).

Recommendation

Apply the official kernel patch that moves the lock acquisition before the socket state check. Reboot the system after updating the kernel.

Other vulnerabilities in Linux kernel

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Original NVD description (English source)

In the Linux kernel, the following vulnerability has been resolved: net/smc: fix TOCTOU race between smc_listen_out() and listener close smc_listen_out() reads lsmc->sk.sk_state without the listener lock, then acquires lock_sock_nested() only after the check passes. This opens a window where smc_close_active() can transition the listener to SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept queue, and release the lock, all between the lockless read and the delayed lock acquisition: smc_listen_work (smc_hs_wq) smc_close_active() ------------------------------- ------------------------- release_sock(child) if (sk_state == SMC_LISTEN) TRUE lock_sock(listener) sk_state = SMC_CLOSED smc_close_cleanup_listen() release_sock(listener) flush_work(tcp_listen_work) lock_sock_nested(listener) smc_accept_enqueue(listener, child) /* child enqueued on dead listener */ smc_close_active() flushes only tcp_listen_work. Work items already dispatched onto smc_hs_wq for the CLC handshake continue running unguarded. smc_accept_enqueue() takes a sock_hold() on the child that is never released, so the child smc_sock, its clcsock, and the reference all leak. A remote peer that opens TCP connections while the server calls close() can exhaust kernel memory. Move lock_sock_nested() to before the sk_state check so that the test and the enqueue are atomic under the listener lock.

Vulnerability data from NVD (NIST) · CISA KEV · EPSS