CVE-2026-23391 json
netfilter: xt_CT: drop pending enqueued packets on template removal
published 2026-03-25 7 mo ago modified 2026-10-19 20 d ago also EUVD-2026-15392
- cvss
- 7.8
- version 3.1, CNA
- cisa kev
- Not listed
- not in CISA's catalog
- epss
- 0.1%
- EPSS 0.1% chance of exploitation in 30 days, percentile 2%
- public exploits
- 0
- none known
Summary
In the Linux kernel, the following vulnerability has been resolved:
netfilter: xt_CT: drop pending enqueued packets on template removal
Templates refer to objects that can go away while packets are sitting in nfqueue refer to:
- helper, this can be an issue on module removal. - timeout policy, nfnetlink_cttimeout might remove it.
The use of templates with zone and event cache filter are safe, since this just copies values.
Flush these enqueued packets in case the template rule gets removed.
Patch / fix
- Linux Linux 5.10.253, 5.15.203, 6.1.167, 6.6.130, 6.12.78, 6.18.20, 6.19.10, 7.0
- linux Debian 12 6.1.170-1
- linux Debian 13 6.12.85-1
- linux Debian 14 6.19.10-1
debian advisories DEBIAN-CVE-2026-23391
- linux Ubuntu 22.04 LTS 5.15.0-186.196
- linux Ubuntu 24.04 LTS 6.8.0-136.136
- linux-aws Ubuntu 22.04 LTS 5.15.0-1112.119
- linux-aws Ubuntu 24.04 LTS 6.8.0-1061.64
- linux-gcp Ubuntu 22.04 LTS 5.15.0-1112.122
- linux-gcp Ubuntu 24.04 LTS 6.8.0-1064.72
- linux-gke Ubuntu 22.04 LTS 5.15.0-1108.114
- linux-gke Ubuntu 24.04 LTS 6.8.0-1059.67
ubuntu advisories UBUNTU-CVE-2026-23391
Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0
- kernel-64kb SLE Module for Basesystem 15 SP7 6.4.0-150700.53.55.1
- kernel-syms SLE Module for Development Tools 15 SP7 6.4.0-150700.53.55.1
- kernel-azure SLE Module for Public Cloud 15 SP7 6.4.0-150700.53.55.1
- kernel-source SLE Module for Development Tools 15 SP7, SLE Module for Basesystem 15 SP7 6.4.0-150700.53.55.1
- kernel-default SLE Workstation Extension 15 SP7, SLE Module for Legacy 15 SP7, SLE Module for Basesystem 15 SP7 +2 more 6.4.0-150700.53.55.1
- kernel-zfcpdump SLE Module for Basesystem 15 SP7 6.4.0-150700.53.55.1
- kernel-obs-build SLE Module for Development Tools 15 SP7 6.4.0-150700.53.55.1
- kernel-default-base SLE Module for Basesystem 15 SP7 6.4.0-150700.53.55.1.150700.17.33.1
suse advisories SUSE-SU-2026:2238-1SUSE-SU-2026:21834-1
- git.kernel.org/stable/c/55445134d42b84cb0a272e42c98d233ca65eca83 commit
- git.kernel.org/stable/c/cc57506dd66555899560b9c0f24e813f034e12ec commit
- git.kernel.org/stable/c/d2d0bae0c9a2a17b6990a2966f5cdce0813d6256 commit
- git.kernel.org/stable/c/63b8097cea1923fe82cd598068d0796da8c015ec commit
- git.kernel.org/stable/c/19a230dec6bb8928e3f96387f9085cf2c79bcef9 commit
- git.kernel.org/stable/c/cb549925875fa06dd155e49db4ac2c5044c30f9c commit
- git.kernel.org/stable/c/777d02efe3d630cca4c1b63962cec17c57711325 commit
- git.kernel.org/stable/c/f62a218a946b19bb59abdd5361da85fa4606b96b commit
Vendor advisories
What the vendors themselves say about their products: affected, fixed or not affected, and what to do.
red hat product security vex CVE-2026-23391 updated cvss 5.5
kernel: netfilter: xt_CT: drop pending enqueued packets on template removal
-
Red Hat Enterprise Linux 6 perf, kernel, python-perf, kernel-kdump, kernel-firmware, kernel-bootwrapper, +1 moreaffected: no fix planned “Out of support scope”
-
Red Hat Enterprise Linux 7 perf, kernel, bpftool, kernel-rt, python-perf, kernel-kdump, +8 more Red Hat Enterprise Linux 8 perf, kernel, bpftool, kernel-rt, kernel-core, kernel-tools, +29 more Red Hat Enterprise Linux 9 rv, perf, rtla, kernel, bpftool, libperf, +83 more Red Hat Enterprise Linux 10 kernelaffected: no fix available “Fix deferred”
Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf
cisa ICSA-26-295-11 updated cvss 7.8
Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP
-
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.7 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.7 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.7affected: mitigation, no fix available
Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf
cisa ICSA-26-295-16 updated cvss 7.8
Siemens SIMATIC S7-1500 TM MFP
-
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystemaffected: mitigation, no fix available
Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf
cisa ICSA-26-209-04 updated cvss 7.8
Siemens SIMATIC S7-1500 CPU 1518(F)-4 PN/DP MFP
-
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AB0) >= 3.1.6 Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP (6ES7518-4AX00-1AC0) >= 3.1.6 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AB0) >= 3.1.6 Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP (6ES7518-4FX00-1AC0) >= 3.1.6 Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP (6AG1518-4AX00-4AC0) >= 3.1.6affected: mitigation, no fix available
Facts from CISA's republication of the vendor's own advisory (CSAF); the linked advisory is the authoritative source. CISA notification · csaf
CISA SSVC
- Exploitation
- none
- Automatable
- no
- Technical impact
- total
- Assessed
- 23 d ago
Exploit prediction
0.13% chance of exploitation in the next 30 days, higher than 2% of all scored CVEs (FIRST EPSS, 2026-11-08).
CVSS scores
| assigned by | version | score | vector |
|---|---|---|---|
| CNA | 3.1 | 7.8 | CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H |
Affected products
- Linux Linux
- Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP
- Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP
- Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem
- Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP
Classification
- Weakness
-
- CWE-416 Use After Free
- Technology feeds
References
-
git.kernel.org
/stable/c/55445134d42b84cb0a272e42c98d233ca65eca83
patch
-
git.kernel.org
/stable/c/cc57506dd66555899560b9c0f24e813f034e12ec
patch
-
git.kernel.org
/stable/c/d2d0bae0c9a2a17b6990a2966f5cdce0813d6256
patch
-
git.kernel.org
/stable/c/63b8097cea1923fe82cd598068d0796da8c015ec
patch
-
git.kernel.org
/stable/c/19a230dec6bb8928e3f96387f9085cf2c79bcef9
patch
-
git.kernel.org
/stable/c/cb549925875fa06dd155e49db4ac2c5044c30f9c
patch
-
git.kernel.org
/stable/c/777d02efe3d630cca4c1b63962cec17c57711325
patch
-
git.kernel.org
/stable/c/f62a218a946b19bb59abdd5361da85fa4606b96b
patch
- cert-portal.siemens.com /productcert/html/ssa-082556.html
- cert-portal.siemens.com /productcert/html/ssa-019113.html
- cert-portal.siemens.com /productcert/html/ssa-457936.html
- cert-portal.siemens.com /productcert/html/ssa-784472.html
Sources
- CVE List CVE-2026-23391
- NVD CVE-2026-23391
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