Linux Kernel TCP stack Vulnerability Rated 7.5 CVSS

Status: UPDATED  |  Advisory ID: CVE-2026-74692

Key Details

Affected Products, Subsystems & Sectors

What to Know

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. (NVD)

What to Do

Monitor Linux's web page for any future patch releases.

References