{"id":"CVE-2026-74692","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74692","summary":"net/smc: fix TOCTOU race between smc_listen_out() and listener close","details":"In the Linux kernel, the following vulnerability has been resolved:\n\nnet/smc: fix TOCTOU race between smc_listen_out() and listener close\n\nsmc_listen_out() reads lsmc->sk.sk_state without the listener lock,\nthen acquires lock_sock_nested() only after the check passes. This\nopens a window where smc_close_active() can transition the listener\nto SMC_CLOSED, call smc_close_cleanup_listen() to drain the accept\nqueue, and release the lock, all between the lockless read and the\ndelayed lock acquisition:\n\n  smc_listen_work (smc_hs_wq)          smc_close_active()\n  -------------------------------      -------------------------\n  release_sock(child)\n  if (sk_state == SMC_LISTEN) TRUE\n                                        lock_sock(listener)\n                                        sk_state = SMC_CLOSED\n                                        smc_close_cleanup_listen()\n                                        release_sock(listener)\n                                        flush_work(tcp_listen_work)\n  lock_sock_nested(listener)\n  smc_accept_enqueue(listener, child) /* child enqueued on dead listener */\n\nsmc_close_active() flushes only tcp_listen_work. Work items already\ndispatched onto smc_hs_wq for the CLC handshake continue running\nunguarded. smc_accept_enqueue() takes a sock_hold() on the child that\nis never released, so the child smc_sock, its clcsock, and the\nreference all leak. A remote peer that opens TCP connections while the\nserver calls close() can exhaust kernel memory.\n\nMove lock_sock_nested() to before the sk_state check so that the test\nand the enqueue are atomic under the listener lock.","published":"2026-08-22T15:32:55.873Z","modified":"2026-08-24T11:47:21.000902883Z","cvss":null,"epss":{"score":0.00173,"percentile":0.06711,"asOf":"2026-08-24"},"cisaKev":null,"exploitsKnown":0,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"5.15.216"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/00f89433777236ced4771211047fb5d4cd581cea"},{"type":"WEB","url":"https://git.kernel.org/stable/c/01865e1ddb126b25ac9eba5cdd7ec49e11183a64"},{"type":"WEB","url":"https://git.kernel.org/stable/c/185a4caeecabc150106deda1da170b09f2ad803f"},{"type":"WEB","url":"https://git.kernel.org/stable/c/53c7938d8bcfde3296ec1a347ba2a9393c1fdcfa"},{"type":"WEB","url":"https://git.kernel.org/stable/c/78e5ebcd1c10ed7c8bda0a99e0abd5b62da86d67"},{"type":"WEB","url":"https://git.kernel.org/stable/c/feb71634bb1abab3e8fb5cde874b27001cc1282e"},{"type":"WEB","url":"https://git.kernel.org/stable/c/ff5bcd804b5bc5c64736b7d318c20e12ea9506b8"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74692.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74692"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-24T11:47:21.000902883Z"}}