{"cve":"CVE-2026-98255","nvd":{"published":"2026-10-06T09:18:14.210","modified":"2026-10-19T10:18:26.500","status":"Received","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.","cvss_v4":null,"cvss_v3":null,"cwes":[],"references":["https://git.kernel.org/stable/c/07cacab90290f795bad2e566790f4ba8e84cdf5f","https://git.kernel.org/stable/c/1c8448db5cf35a13d82b0c9004ffdb49358883e7","https://git.kernel.org/stable/c/6eb9b697f50b73b9684e466c1e97f4ca8e947a59","https://git.kernel.org/stable/c/8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed","https://git.kernel.org/stable/c/8309dc2cc360056aa9cd2acfbfc25930798c3b66"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:57:46.668721662+00:00"},"epss":{"cve":"CVE-2026-98255","score":0.00177,"percentile":0.07178,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}