netfilter: conntrack: tcp: do not force CLOSE on invalid-seq RST without direction check
In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: tcp: do not force CLOSE on invalid-seq RST without direction check An unintended behavior in the TCP conntrack state machine allows a connection to be forced into the CLOSE state using an RST packet with an invalid sequence number. Specifically, after a SYN packet is observed, an RST with an invalid SEQ can transition the conntrack entry to TCP_CONNTRACK_CLOSE, regardless of whether the RST corresponds to the expected reply direction. The relevant code path assumes the RST is a response to an outgoing SYN, but does not validate packet direction or ensure that a matching SYN was actually sent in the opposite direction. As a result, a crafted packet sequence consisting of a SYN followed by an invalid-sequence RST can prematurely terminate an active NAT entry. This makes connection teardown easier than intended. So, tighten the state transition logic to ensure that RST-triggered CLOSE transitions only occur when the RST is a valid response to a previously observed SYN in the correct direction.
CVE-2026-63913
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-2026-63913
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": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "2006979a15af5404bf932a325357683c0bac1656",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "6476c17d536dbd321c073242e762ddb2713a1238",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "f5547bebc416d56f56fb5b86dc20aabfa42165a0",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "2bb6d82b586ea5a4cb73bbdd6b7432e96096bc77",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "f206def4e86d810f927ba1d8e322ea72b29bce58",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "b98ab51c45c5608a1c19ce7fd17a3032469bb83f",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "d67c6adee8d1b65330d0174c4c367faba14e80a8",
"versionType": "git"
},
{
"status": "affected",
"version": "9fb9cbb1082d6b31fb45aa1a14432449a0df6cf1",
"lessThan": "bed6e04be8e6b9133d8b16d5a42d0e0ce674fa9a",
"versionType": "git"
}
],
"programFiles": [
"net/netfilter/nf_conntrack_proto_tcp.c"
],
"defaultStatus": "unaffected"
},
{
"repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
"vendor": "Linux",
"product": "Linux",
"versions": [
{
"status": "affected",
"version": "2.6.15"
},
{
"status": "unaffected",
"version": "0",
"lessThan": "2.6.15",
"versionType": "semver"
},
{
"status": "unaffected",
"version": "5.10.259",
"versionType": "semver",
"lessThanOrEqual": "5.10.*"
},
{
"status": "unaffected",
"version": "5.15.210",
"versionType": "semver",
"lessThanOrEqual": "5.15.*"
},
{
"status": "unaffected",
"version": "6.1.176",
"versionType": "semver",
"lessThanOrEqual": "6.1.*"
},
{
"status": "unaffected",
"version": "6.6.143",
"versionType": "semver",
"lessThanOrEqual": "6.6.*"
},
{
"status": "unaffected",
"version": "6.12.93",
"versionType": "semver",
"lessThanOrEqual": "6.12.*"
},
{
"status": "unaffected",
"version": "6.18.35",
"versionType": "semver",
"lessThanOrEqual": "6.18.*"
},
{
"status": "unaffected",
"version": "7.0.12",
"versionType": "semver",
"lessThanOrEqual": "7.0.*"
},
{
"status": "unaffected",
"version": "7.1",
"versionType": "original_commit_for_fix",
"lessThanOrEqual": "*"
}
],
"programFiles": [
"net/netfilter/nf_conntrack_proto_tcp.c"
],
"defaultStatus": "affected"
}
]- Related CVEs
- CVE-2026-63913
Source reference:
/cveMetadata/cveId
Publisher severity
high
Source reference: /containers/cna/metrics
- Event
- #40888 · Revision 1
- Added to Heist Feed
- Publisher date