{"id":"CVE-2026-74696","aliases":[],"url":"https://o3.security/vulnerability/CVE-2026-74696","summary":"tcp: fix TFO max_qlen accounting across reuseport migration","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: fix TFO max_qlen accounting across reuseport migration\n\nA listener's TCP_FASTOPEN max_qlen stops being accurate and lets through\nfar more pending Fast Open requests than it was configured for.\n\nThis only shows up with SO_REUSEPORT listener migration, where closing a\nlistener hands its still-pending TFO children over to a surviving one.\n\nfastopenq.qlen is charged in tcp_fastopen_create_child() when the child\nis created and uncharged in reqsk_fastopen_remove() when the handshake\ncompletes.  The uncharge follows rsk_listener of the request the child\npoints at, and inet_reqsk_clone() has repointed the child at a new\nrequest owned by the new listener, so the ++ and the -- land on two\ndifferent sockets.  The new listener's qlen drifts negative and its\nlimit no longer binds.\n\nCharge the new listener during migration, like reqsk_queue_migrated()\nalready does for queue->young and queue->qlen.","published":"2026-08-22T15:32:58.414Z","modified":"2026-08-24T11:47:18.959061314Z","cvss":null,"epss":null,"cisaKev":null,"exploitsKnown":null,"affectedPackages":[{"ecosystem":"Linux","name":"Kernel","fixedVersion":"5.15.216"}],"fix":null,"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/585fc5247d14939a561056aa2addd9b7c2b1f670"},{"type":"WEB","url":"https://git.kernel.org/stable/c/6e10ee56524a26b250229ad348637825646ddb88"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a0ab2ba83e35159d81cec830a92e885ecf8139be"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a66e869cf0c90c1e47ae75f72b6482acbfc808ff"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b6247e0f96bd825ffb2005257f6177b5e642dee6"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d974618b2097453778389d385e3741629c40e0a3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/e98f0d80b9cccb5f828425d2004f9686e7d1ae24"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74696.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-74696"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"provenance":{"sources":["OSV.dev","FIRST.org (EPSS)"],"lastVerified":"2026-08-24T11:47:18.959061314Z"}}