CVE-2026-98255tcp: exclude old ACKs from tcp fast path
- —Not scoredno CVSS score yet
- 0.18%Exploitation in 30 daysEPSS · top 93% of all CVEs
- NoKnown exploitednot in CISA's KEV catalog
- NonePublic exploitsnone known yet
Description
In the Linux kernel, the following vulnerability has been resolved: tcp: exclude old ACKs from tcp fast path Exclude old ACKs before SND.UNA from the tcp fast path as well as ACKs after SND.NXT. Such ACKs will fall through to the slow path, where tcp_ack() performs the appropriate validation and challenge ACK handling according to RFC5961 and Commit 3d501dd326fb1c7 ("tcp: do not accept ACK of bytes we never sent"). This prevents old ACKs from being accepted or modifying connection state as part of the fast path before appropriate ACK validation is applied. In particular, this prevents payload carried by a segment with an excessively old ACK from advancing RCV.NXT before the ACK is rejected.
Timeline
ID reserved
By Linux
- 11 days later
· 11 days later
Published
- 13 days later
· 13 days later
Record updated
Changes after publication (a new score, a public exploit, EPSS crossing 1, 10 or 50 %, leaving KEV) are kept since November 2026; earlier ones are not known.
Scores
No CVSS score yet: neither the CNA, CISA nor NVD has scored this CVE. NVD status: Received.
- EPSS (exploitation in 30 days)
- 0.18% · top 93% of all CVEs (14 Nov 2026)
The list uses the assigner's score when there is one, then CISA's, then NVD's: Not scored.
Affected products
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < 07cacab90290f795bad2e566790f4ba8e84cdf5f
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < 6eb9b697f50b73b9684e466c1e97f4ca8e947a59
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < b86e1e5a4bbcbbccde8b7a3d3486604b581f6628
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < 1c8448db5cf35a13d82b0c9004ffdb49358883e7
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < 8309dc2cc360056aa9cd2acfbfc25930798c3b66
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < ff037920c688ae6ca1153fec01e90e6782712455
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < 8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed
- affected 31770e34e43d6c8dee129bfee77e56c34e61f0e5 – < f81e6c3fb06327bc49cdd6e559845293ba06a704
- affected 4.14
- unaffected < 4.14
- unaffected 5.10.271 – ≤ 5.10.*
- unaffected 5.15.222 – ≤ 5.15.*
- unaffected 6.1.189 – ≤ 6.1.*
- unaffected 6.6.158 – ≤ 6.6.*
- unaffected 6.12.112 – ≤ 6.12.*
- unaffected 6.18.54 – ≤ 6.18.*
- unaffected 7.2.8 – ≤ 7.2.*
- unaffected 7.3 – ≤ *
References
References8
- https://git.kernel.org/stable/c/07cacab90290f795bad2e566790f4ba8e84cdf5f (opens in a new tab)
- https://git.kernel.org/stable/c/6eb9b697f50b73b9684e466c1e97f4ca8e947a59 (opens in a new tab)
- https://git.kernel.org/stable/c/b86e1e5a4bbcbbccde8b7a3d3486604b581f6628 (opens in a new tab)
- https://git.kernel.org/stable/c/1c8448db5cf35a13d82b0c9004ffdb49358883e7 (opens in a new tab)
- https://git.kernel.org/stable/c/8309dc2cc360056aa9cd2acfbfc25930798c3b66 (opens in a new tab)
- https://git.kernel.org/stable/c/ff037920c688ae6ca1153fec01e90e6782712455 (opens in a new tab)
- https://git.kernel.org/stable/c/8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed (opens in a new tab)
- https://git.kernel.org/stable/c/f81e6c3fb06327bc49cdd6e559845293ba06a704 (opens in a new tab)
Sources
The same CVE in the primary databases and aggregators, to check against.
- CVE.org record (opens in a new tab)
- CVE List JSON (GitHub) (opens in a new tab)
- NVD (opens in a new tab)
- FIRST EPSS (opens in a new tab)
- EUVD EUVD-2026-93183 (opens in a new tab)
- OSV.dev (opens in a new tab)
- GitHub Advisories (opens in a new tab)
- CIRCL Vulnerability-Lookup (opens in a new tab)
Badge for a README or a ticket
[](https://cveledger.app/cve/CVE-2026-98255)Record last updated .