Medium 5.5Published Jun 25, 2026

CVE-2026-53269netfilter: synproxy: add mutex to guard hook reference counting

Updated under an hour ago (Oct 27, 2026, 7:23 AM ET)

Does this affect you?

It affects Linux and 5 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

Do this next

Start free and add your stack

Free account, 1 product

Every CVE for Linux

Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: netfilter: synproxy: add mutex to guard hook reference counting As the synproxy infrastructure register netfilter hooks on-demand when a user adds the first iptables target or nftables expression, if done concurrently they can race each other. Introduce a mutex to serialize the refcount control blocks access from both frontends. While a per namespace mutex might be more efficient, it is not needed for target/expression like SYNPROXY.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from ad49d86e07a497e834cb06f2b151dccd75f8e148 before 0ec9ddc1bda261a2c57636c74c8b4e53000102c9; from ad49d86e07a497e834cb06f2b151dccd75f8e148 before 56ffbe3a08c01dcdb0d6adee9ce1e535bfb3b389; from ad49d86e07a497e834cb06f2b151dccd75f8e148 before debc57b83d5b323df74bf010c8d50fe26ad2ed6b; from ad49d86e07a497e834cb06f2b151dccd75f8e148 before 0f8ba5e4c53d2e4a536aa68140beda9fe59b2f88; from ad49d86e07a497e834cb06f2b151dccd75f8e148 before 640441348258220e78daed40528b85b8afcedab6; from ad49d86e07a497e834cb06f2b151dccd75f8e148 before aaf80701dc2f7a48fe543961e21f8ca3924d587c; from ad49d86e07a497e834cb06f2b151dccd75f8e148 before fbf0591275f50eae5733c3d7a8cd6c1e79933ffa; from ad49d86e07a497e834cb06f2b151dccd75f8e148 before 2fcba19caaeb2a33017459d3430f057967bb91b6	CNA record
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 5.3 before 5.10.259; from 5.11 before 5.15.210; from 5.16 before 6.1.176; from 6.2 before 6.6.143; from 6.7 before 6.12.94; from 6.13 before 6.18.36; from 6.19 before 7.0.13; 7.1; and 5 more ranges	NVD

References

References

https://git.kernel.org/stable/c/0ec9ddc1bda261a2c57636c74c8b4e53000102c9	patch
https://git.kernel.org/stable/c/56ffbe3a08c01dcdb0d6adee9ce1e535bfb3b389	patch
https://git.kernel.org/stable/c/debc57b83d5b323df74bf010c8d50fe26ad2ed6b	patch
https://git.kernel.org/stable/c/0f8ba5e4c53d2e4a536aa68140beda9fe59b2f88	patch
https://git.kernel.org/stable/c/640441348258220e78daed40528b85b8afcedab6	patch
https://git.kernel.org/stable/c/aaf80701dc2f7a48fe543961e21f8ca3924d587c	patch
https://git.kernel.org/stable/c/fbf0591275f50eae5733c3d7a8cd6c1e79933ffa	patch
https://git.kernel.org/stable/c/2fcba19caaeb2a33017459d3430f057967bb91b6	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-457936.html
1–10 of 11

The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.