CVE-2026-98255
tcp: exclude old ACKs from tcp fast path
No known exploitation. EPSS puts it in the 7th percentile. Fixed versions are out.
What to do
Find your product and version, then upgrade to the build on the right.
- LinuxAffected: ≥ 31770e34e43d6c8dee129bfee77e56c34e61f0e5, < 07cacab90290f795bad2e566790f4ba8e84cdf5fUpgrade to: 07cacab90290f795bad2e566790f4ba8e84cdf5fAffected: ≥ 31770e34e43d6c8dee129bfee77e56c34e61f0e5, < 6eb9b697f50b73b9684e466c1e97f4ca8e947a59Upgrade to: 6eb9b697f50b73b9684e466c1e97f4ca8e947a59Affected: ≥ 31770e34e43d6c8dee129bfee77e56c34e61f0e5, < b86e1e5a4bbcbbccde8b7a3d3486604b581f6628Upgrade to: b86e1e5a4bbcbbccde8b7a3d3486604b581f6628Affected: ≥ 31770e34e43d6c8dee129bfee77e56c34e61f0e5, < 1c8448db5cf35a13d82b0c9004ffdb49358883e7Upgrade to: 1c8448db5cf35a13d82b0c9004ffdb49358883e7 + 4 more branchesStated by: CVE record
Versions as the sources state them. Full version matrix after sign-in
What it is
From the CVE record
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.
In plain language
No plain-language summary for this CVE yet.
Exploitation
Where each signal puts this CVE on the scale from published to confirmed exploited.
- CISA KEV
Not in the catalog. CISA has not confirmed exploitation.
- Public exploits
No public exploit or proof of concept found in the sources we track.
- EPSS
0.2% chance of exploitation activity in the next 30 days, which ranks it in the 7th percentile of scored CVEs.
Exploit Prediction Scoring System, FIRST.org. A probability, not a confirmation.
Lifecycle
2 events over 0 days, from the signal feeds we watch.
- Publishedrecord updated
Affected products
Sources
References in the record
- git.kernel.org/stable/c/07cacab90290f795bad2e566790f4ba8e84cdf5f
- git.kernel.org/stable/c/6eb9b697f50b73b9684e466c1e97f4ca8e947a59
- git.kernel.org/stable/c/b86e1e5a4bbcbbccde8b7a3d3486604b581f6628
And 5 more references. See all after sign-in
In the news
Watch the software you run.
My Stack ranks new CVEs for your products by real-world exploitation, so the next serious one reaches you without reading every advisory.
We'll flag the next CVE, public exploit or patch for Linux, not every advisory.
A free account adds
- The full version matrix and every affected product
- Exploit links, proofs of concept and Metasploit modules
- Email alerts for the products you watch
- The same data over REST API, MCP and CLI