{"id":"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-\u003eyoung and queue-\u003eqlen.","modified":"2026-08-26T03:30:37.756997133Z","published":"2026-08-22T15:32:58.414Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/74xxx/CVE-2026-74696.json"},"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"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"54b92e84193749c9968aff2dd46e3b0f42643e18"},{"fixed":"e98f0d80b9cccb5f828425d2004f9686e7d1ae24"},{"fixed":"b6247e0f96bd825ffb2005257f6177b5e642dee6"},{"fixed":"585fc5247d14939a561056aa2addd9b7c2b1f670"},{"fixed":"6e10ee56524a26b250229ad348637825646ddb88"},{"fixed":"a66e869cf0c90c1e47ae75f72b6482acbfc808ff"},{"fixed":"d974618b2097453778389d385e3741629c40e0a3"},{"fixed":"a0ab2ba83e35159d81cec830a92e885ecf8139be"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-74696.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.14.0"},{"fixed":"5.15.216"}]},{"type":"ECOSYSTEM","events":[{"introduced":"5.16.0"},{"fixed":"6.1.183"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.152"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.104"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.45"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.9"}]}],"database_specific":{"source":"https://storage.googleapis.com/osv-test-cve-osv-conversion/osv-output/CVE-2026-74696.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"}]}