{"id":"CVE-2026-98255","revision":"6f0ac8954770488786e75fdbeacddc40","records":[{"revision":"6f0ac8954770488786e75fdbeacddc40","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-98255","aliases":[],"title":"tcp: exclude old ACKs from tcp fast path","description":"In the Linux kernel, the following vulnerability has been resolved:\n\ntcp: exclude old ACKs from tcp fast path\n\nExclude old ACKs before SND.UNA from the tcp fast path\nas well as ACKs after SND.NXT.\n\nSuch ACKs will fall through to the slow path, where tcp_ack()\nperforms the appropriate validation and challenge ACK handling\naccording to RFC5961 and Commit 3d501dd326fb1c7 (\"tcp: do not\naccept ACK of bytes we never sent\").\n\nThis prevents old ACKs from being accepted\nor modifying connection state as part of the fast path before\nappropriate ACK validation is applied.\nIn particular, this prevents payload carried by a segment with\nan excessively old ACK from advancing RCV.NXT before the ACK\nis rejected.","state":0,"publishedAt":"2026-10-06T08:45:21.397+00:00","modifiedAt":"2026-10-19T09:16:26.522+00:00","affected":[{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"unaffected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/ipv4/tcp_input.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"07cacab90290f795bad2e566790f4ba8e84cdf5f\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"6eb9b697f50b73b9684e466c1e97f4ca8e947a59\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"b86e1e5a4bbcbbccde8b7a3d3486604b581f6628\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"1c8448db5cf35a13d82b0c9004ffdb49358883e7\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"8309dc2cc360056aa9cd2acfbfc25930798c3b66\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"ff037920c688ae6ca1153fec01e90e6782712455\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        },\n                        {\n                            \"version\": \"31770e34e43d6c8dee129bfee77e56c34e61f0e5\",\n                            \"lessThan\": \"f81e6c3fb06327bc49cdd6e559845293ba06a704\",\n                            \"status\": \"affected\",\n                            \"versionType\": \"git\"\n                        }\n                    ]\n                }"},{"ecosystem":"Vendor product","name":"Linux","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"product\": \"Linux\",\n                    \"vendor\": \"Linux\",\n                    \"defaultStatus\": \"affected\",\n                    \"repo\": \"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git\",\n                    \"programFiles\": [\n                        \"net/ipv4/tcp_input.c\"\n                    ],\n                    \"versions\": [\n                        {\n                            \"version\": \"4.14\",\n                            \"status\": \"affected\"\n                        },\n                        {\n                            \"version\": \"0\",\n                            \"lessThan\": \"4.14\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.10.271\",\n                            \"lessThanOrEqual\": \"5.10.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"5.15.222\",\n                            \"lessThanOrEqual\": \"5.15.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.1.189\",\n                            \"lessThanOrEqual\": \"6.1.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.6.158\",\n                            \"lessThanOrEqual\": \"6.6.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.12.112\",\n                            \"lessThanOrEqual\": \"6.12.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"6.18.54\",\n                            \"lessThanOrEqual\": \"6.18.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.2.8\",\n                            \"lessThanOrEqual\": \"7.2.*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"semver\"\n                        },\n                        {\n                            \"version\": \"7.3\",\n                            \"lessThanOrEqual\": \"*\",\n                            \"status\": \"unaffected\",\n                            \"versionType\": \"original_commit_for_fix\"\n                        }\n                    ]\n                }"}],"metrics":[],"references":["https://git.kernel.org/stable/c/07cacab90290f795bad2e566790f4ba8e84cdf5f","https://git.kernel.org/stable/c/6eb9b697f50b73b9684e466c1e97f4ca8e947a59","https://git.kernel.org/stable/c/b86e1e5a4bbcbbccde8b7a3d3486604b581f6628","https://git.kernel.org/stable/c/1c8448db5cf35a13d82b0c9004ffdb49358883e7","https://git.kernel.org/stable/c/8309dc2cc360056aa9cd2acfbfc25930798c3b66","https://git.kernel.org/stable/c/ff037920c688ae6ca1153fec01e90e6782712455","https://git.kernel.org/stable/c/8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed","https://git.kernel.org/stable/c/f81e6c3fb06327bc49cdd6e559845293ba06a704"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-98255","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-98255","identifiers":["CVE-2026-98255"]},"retained":false,"historicalAffected":[]}],"coverage":[]}