tcp: exclude old ACKs from tcp fast path
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.
CVE-2026-98255
Primary source · Revision 1
Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.
Security context
Source reference: cve:CVE-2026-98255
Linux
Source reference: /containers/cna/affected/0/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Linux
Source reference: /containers/cna/affected/1/product
- Affected versions
- Not stated in this record
- Fixed versions
- Not stated in this record
- Prerequisites
- Not stated in this record
Structured affected-version data
Original package identities and version rules from this source.
[
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "07cacab90290f795bad2e566790f4ba8e84cdf5f",
"versionType": "git"
},
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "6eb9b697f50b73b9684e466c1e97f4ca8e947a59",
"versionType": "git"
},
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "b86e1e5a4bbcbbccde8b7a3d3486604b581f6628",
"versionType": "git"
},
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "1c8448db5cf35a13d82b0c9004ffdb49358883e7",
"versionType": "git"
},
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "8309dc2cc360056aa9cd2acfbfc25930798c3b66",
"versionType": "git"
},
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "ff037920c688ae6ca1153fec01e90e6782712455",
"versionType": "git"
},
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "8205ac5ddb42a1843fa8d6a8c295b5c7f4f8c6ed",
"versionType": "git"
},
{
"status": "affected",
"version": "31770e34e43d6c8dee129bfee77e56c34e61f0e5",
"lessThan": "f81e6c3fb06327bc49cdd6e559845293ba06a704",
"versionType": "git"
}
],
"programFiles": [
"net/ipv4/tcp_input.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "4.14"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "4.14",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.271",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.222",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.189",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.158",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.112",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.54",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.2.8",
"versionType": "semver",
"lessThanOrEqual": "7.2.*"
},
{
"status": "unaffected",
"version": "7.3",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/ipv4/tcp_input.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-98255
Source reference:
/cveMetadata/cveId
Publisher severity
No explicit severity was provided.
- Event
- #38334 · Revision 1
- Added to Heist Feed
- Publisher date