{"id":"CVE-2026-68118","summary":"tcp: challenge ACK for non-exact RST in SYN-RECEIVED","details":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: challenge ACK for non-exact RST in SYN-RECEIVED\n\nThe SYN-RECEIVED request-socket path in tcp_check_req() accepts an\nin-window RST without requiring SEG.SEQ to exactly match RCV.NXT.  A\nnon-exact RST therefore removes the request instead of eliciting a\nchallenge ACK.\n\nRFC 9293 section 3.10.7.4 applies the RFC 5961 reset check in\nSYN-RECEIVED: an exact RST resets the connection, while a non-exact\nin-window RST must trigger a challenge ACK and be dropped.\n\nApply that check before the ACK-field validation, following the RFC\nsequence-number, RST, then ACK processing order.  Factor the per-netns\nchallenge ACK quota out of tcp_send_challenge_ack() so request sockets\ncan share it.  Use the request socket's send_ack() callback and its own\nout-of-window ACK timestamp to send and rate-limit the response.","modified":"2026-11-01T02:30:51.365641701Z","published":"2026-08-10T11:58:38Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68118.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/0fe4636665d14a258de70b4f3e8248e6d42038f1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/22cec809b048495310f206d9abbcdbbfbdce3ae3"},{"type":"WEB","url":"https://git.kernel.org/stable/c/234f9ffbd9b2c1b24ec67200ea3cff07401bec48"},{"type":"WEB","url":"https://git.kernel.org/stable/c/8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49"},{"type":"WEB","url":"https://git.kernel.org/stable/c/a28c4fcbf774e23b4779cae468e3497a5ad1f4a1"},{"type":"WEB","url":"https://git.kernel.org/stable/c/c5dc463cc60eb26079b19607c9dbda76491dad05"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68118.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-68118"},{"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":"282f23c6ee343126156dd41218b22ece96d747e3"},{"fixed":"c5dc463cc60eb26079b19607c9dbda76491dad05"},{"fixed":"8b0a3a094f4cae2fb92e4d08d4eef7246a9d9c49"},{"fixed":"0fe4636665d14a258de70b4f3e8248e6d42038f1"},{"fixed":"234f9ffbd9b2c1b24ec67200ea3cff07401bec48"},{"fixed":"22cec809b048495310f206d9abbcdbbfbdce3ae3"},{"fixed":"a28c4fcbf774e23b4779cae468e3497a5ad1f4a1"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3.0.58"},{"fixed":"3.1"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3.2.37"},{"fixed":"3.3"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"3.4.25"},{"fixed":"3.5"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"86791bbfe5ed7b275be040cfeff049a1624af1b7"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"61f69dc4e40e41b0018f00fa4aeb23d3239556fb"}]},{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"34fb350281ced2a72707a5c0064f69992d440edb"}]}],"versions":["v3.0.101","v3.0.100","v3.0.99","v3.0.98","v3.0.97","v3.0.96","v3.0.95","v3.0.94","v3.0.93","v3.0.92","v3.0.91","v3.0.90","v3.0.89","v3.0.88","v3.0.87","v3.0.86","v3.0.85","v3.0.84","v3.0.83","v3.0.82","v3.0.81","v3.0.80","v3.0.79","v3.0.78","v3.0.77","v3.0.76","v3.0.75","v3.0.74","v3.0.73","v3.0.72","v3.0.71","v3.0.70","v3.0.69","v3.0.68","v3.0.67","v3.0.66","v3.0.65","v3.0.64","v3.0.63","v3.0.62","v3.0.61","v3.0.60","v3.0.59","v3.0.58","v3.2.102","v3.2.101","v3.2.100","v3.2.99","v3.2.98","v3.2.97","v3.2.96","v3.2.95","v3.2.94","v3.2.93","v3.2.92","v3.2.91","v3.2.90","v3.2.89","v3.2.88","v3.2.87","v3.2.86","v3.2.85","v3.2.84","v3.2.83","v3.2.82","v3.2.81","v3.2.80","v3.2.79","v3.2.78","v3.2.77","v3.2.76","v3.2.75","v3.2.74","v3.2.73","v3.2.72","v3.2.71","v3.2.70","v3.2.69","v3.2.68","v3.2.67","v3.2.66","v3.2.65","v3.2.64","v3.2.63","v3.2.62","v3.2.61","v3.2.60","v3.2.59","v3.2.58","v3.2.57","v3.2.56","v3.2.55","v3.2.54","v3.2.53","v3.2.52","v3.2.51","v3.2.50","v3.2.49","v3.2.48","v3.2.47","v3.2.46","v3.2.45","v3.2.44","v3.2.43","v3.2.42","v3.2.41","v3.2.40","v3.2.39","v3.2.38","v3.2.37","v3.4.113","v3.4.112","v3.4.111","v3.4.110","v3.4.109","v3.4.108","v3.4.107","v3.4.106","v3.4.105","v3.4.104","v3.4.103","v3.4.102","v3.4.101","v3.4.100","v3.4.99","v3.4.98","v3.4.97","v3.4.96","v3.4.95","v3.4.94","v3.4.93","v3.4.92","v3.4.91","v3.4.90","v3.4.89","v3.4.88","v3.4.87","v3.4.86","v3.4.85","v3.4.84","v3.4.83","v3.4.82","v3.4.81","v3.4.80","v3.4.79","v3.4.78","v3.4.77","v3.4.76","v3.4.75","v3.4.74","v3.4.73","v3.4.72","v3.4.71","v3.4.70","v3.4.69","v3.4.68","v3.4.67","v3.4.66","v3.4.65","v3.4.64","v3.4.63","v3.4.62","v3.4.61","v3.4.60","v3.4.59","v3.4.58","v3.4.57","v3.4.56","v3.4.55","v3.4.54","v3.4.53","v3.4.52","v3.4.51","v3.4.50","v3.4.49","v3.4.48","v3.4.47","v3.4.46","v3.4.45","v3.4.44","v3.4.43","v3.4.42","v3.4.41","v3.4.40","v3.4.39","v3.4.38","v3.4.37","v3.4.36","v3.4.35","v3.4.34","v3.4.33","v3.4.32","v3.4.31","v3.4.30","v3.4.29","v3.4.28","v3.4.27","v3.4.26","v3.4.25"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-68118.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"3.6.0"},{"fixed":"6.1.191"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.2.0"},{"fixed":"6.6.153"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.105"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.1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