Answer in brief
CVE-2026-98255 records a Unknown severity vulnerability in tcp: exclude old ACKs from tcp fast path. The current sources do not mark it as known exploited. The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps Linux/Linux (generic), Linux/Linux (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| Linux/Linuxgeneric | >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <07cacab90290f795bad2e566790f4ba8e84cdf5f || >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <6eb9b697f50b73b9684e466c1e97f4ca8e947a59 || >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <b86e1e5a4bbcbbccde8b7a3d3486604b581f6628 || >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <1c8448db5cf35a13d82b0c9004ffdb49358883e7 || >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <8309dc2cc360056aa9cd2acfbfc25930798c3b66 || >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <ff037920c688ae6ca1153fec01e90e6782712455 || >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed || >=31770e34e43d6c8dee129bfee77e56c34e61f0e5 <f81e6c3fb06327bc49cdd6e559845293ba06a704 | 07cacab90290f795bad2e566790f4ba8e84cdf5f, 6eb9b697f50b73b9684e466c1e97f4ca8e947a59, b86e1e5a4bbcbbccde8b7a3d3486604b581f6628, 1c8448db5cf35a13d82b0c9004ffdb49358883e7, 8309dc2cc360056aa9cd2acfbfc25930798c3b66, ff037920c688ae6ca1153fec01e90e6782712455, 8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed, f81e6c3fb06327bc49cdd6e559845293ba06a704 |
| Linux/Linuxgeneric | 4.14 | Not reported |
Published upstream
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 6, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Oct 6, 2026
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.
Quoted source text, attributed separately from HOL analysis.