{"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":"2026-08-25T03:51:41.970641613Z","published":"2026-08-10T11:58:38Z","database_specific":{"cna_assigner":"Linux","osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/68xxx/CVE-2026-68118.json"},"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":"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":"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":"0"},{"last_affected":"86791bbfe5ed7b275be040cfeff049a1624af1b7"},{"last_affected":"61f69dc4e40e41b0018f00fa4aeb23d3239556fb"},{"last_affected":"34fb350281ced2a72707a5c0064f69992d440edb"}]},{"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"}]}],"versions":["v3.2.36","v3.4.24","v3.0.57","v3.2.35","v3.0.56","v3.4.23","v3.4.22","v3.0.55","v3.2.34","v3.0.54","v3.4.21","v3.0.53","v3.4.20","v3.4.19","v3.0.52","v3.4.18","v3.0.51","v3.2.33","v3.4.17","v3.0.50","v3.4.16","v3.0.49","v3.2.32","v3.4.15","v3.0.48","v3.0.47","v3.4.14","v3.0.46","v3.2.31","v3.4.13","v3.0.45","v3.2.30","v3.4.12","v3.0.44","v3.4.11","v3.0.43","v3.2.29","v3.0.42","v3.4.10","v3.2.28","v3.4-rc4","v3.0.41","v3.4.9","v3.2.27","v3.0.40","v3.4.8","v3.2.26","v3.4.7","v3.0.39","v3.2.25","v3.2.24","v3.0.38","v3.4.6","v3.2.23","v3.4.5","v3.0.37","v3.4.4","v3.0.36","v3.2.22","v3.2.21","v3.4","v3.4.3","v3.0.35","v3.2.20","v3.0.34","v3.4.2","v3.2.19","v3.4.1","v3.0.33","v3.0.32","v3.2.18","v3.4-rc2","v3.4-rc1","v3.0.31","v3.2.17","v3.4-rc7","v3.4-rc6","v3.4-rc3","v3.4-rc5","v3.2.16","v3.0.30","v3.0.29","v3.0.28","v3.2.15","v3.3","v3.2.14","v3.0.27","v3.2.13","v3.0.26","v3.3-rc6","v3.3-rc3","v3.2.12","v3.0.25","v3.3-rc7","v3.2.11","v3.0.24","v3.3-rc2","v3.3-rc5","v3.2","v3.2.10","v3.3-rc4","v3.2.9","v3.0.23","v3.3-rc1","v3.0.22","v3.2.8","v3.2.7","v3.0.21","v3.2.6","v3.2.5","v3.0.20","v3.2.4","v3.0.19","v3.2.3","v3.2.2","v3.0.18","v3.0.17","v3.2.1","v3.0.16","v3.2-rc4","v3.2-rc7","v3.0.15","v3.2-rc6","v3.2-rc5","v3.0.14","v3.0.13","v3.2-rc3","v3.1","v3.2-rc2","v3.0.12","v3.2-rc1","v3.0.11","v3.0.10","v3.0.9","v3.0.8","v3.1-rc1","v3.1-rc9","v3.1-rc8","v3.0.7","v3.1-rc10","v3.1-rc7","v3.0.6","v3.1-rc3","v3.1-rc2","v3.0.5","v3.0.4","v3.1-rc4","v3.1-rc5","v3.0","v3.1-rc6","v3.0.3","v3.0.2","v3.0.1","v3.0-rc7","v3.0-rc4","v3.0-rc6","v3.0-rc5","v3.0-rc3","v3.0-rc1","v2.6.39","v3.0-rc2","v2.6.38","v2.6.39-rc2","v2.6.39-rc7","v2.6.39-rc5","v2.6.39-rc1","v2.6.38-rc7","v2.6.39-rc6","v2.6.39-rc4","v2.6.39-rc3","v2.6.37","v2.6.38-rc1","v2.6.38-rc8","v2.6.38-rc2","v2.6.38-rc6","v2.6.38-rc5","v2.6.38-rc4","v2.6.38-rc3","v2.6.37-rc4","v2.6.37-rc2","v2.6.36","v2.6.37-rc5","v2.6.37-rc8","v2.6.37-rc7","v2.6.37-rc6","v2.6.37-rc1","v2.6.37-rc3","v2.6.36-rc6","v2.6.35-rc4","v2.6.36-rc8","v2.6.35","v2.6.36-rc7","v2.6.36-rc3","v2.6.36-rc5","v2.6.36-rc4","v2.6.36-rc2","v2.6.36-rc1","v2.6.35-rc5","v2.6.35-rc6","v2.6.34","v2.6.35-rc3","v2.6.35-rc1","v2.6.35-rc2","v2.6.34-rc7","v2.6.34-rc6","v2.6.34-rc5","v2.6.34-rc4","v2.6.34-rc3","v2.6.34-rc2","v2.6.34-rc1","v2.6.33","v2.6.33-rc6","v2.6.33-rc8","v2.6.33-rc4","v2.6.33-rc5","v2.6.33-rc3","v2.6.33-rc7","v2.6.33-rc2","v2.6.32","v2.6.33-rc1","v2.6.32-rc8","v2.6.32-rc7","v2.6.32-rc6","v2.6.31","v2.6.32-rc5","v2.6.32-rc4","v2.6.32-rc2","v2.6.32-rc1","v2.6.32-rc3","v2.6.31-rc9","v2.6.31-rc1","v2.6.31-rc7","v2.6.31-rc8","v2.6.31-rc6","v2.6.30-rc6","v2.6.30","v2.6.31-rc4","v2.6.31-rc5","v2.6.31-rc3","v2.6.31-rc2","v2.6.30-rc7","v2.6.30-rc8","v2.6.30-rc5","v2.6.30-rc3","v2.6.30-rc4","v2.6.30-rc1","v2.6.30-rc2","v2.6.29","v2.6.29-rc8"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