Medium 5.5Published Apr 22, 2026

CVE-2026-31495netfilter: ctnetlink: use netlink policy range checks

Updated under an hour ago (Oct 27, 2026, 12:50 PM ET)

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It affects Linux and 4 other products. Add what you run to find out whether that includes you.

No exploitation reported and no EPSS estimate yet.

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Exploited in the last 30 days

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: use netlink policy range checks Replace manual range and mask validations with netlink policy annotations in ctnetlink code paths, so that the netlink core rejects invalid values early and can generate extack errors. - CTA_PROTOINFO_TCP_STATE: reject values > TCP_CONNTRACK_SYN_SENT2 at policy level, removing the manual >= TCP_CONNTRACK_MAX check. - CTA_PROTOINFO_TCP_WSCALE_ORIGINAL/REPLY: reject values > TCP_MAX_WSCALE (14). The normal TCP option parsing path already clamps to this value, but the ctnetlink path accepted 0-255, causing undefined behavior when used as a u32 shift count. - CTA_FILTER_ORIG_FLAGS/REPLY_FLAGS: use NLA_POLICY_MASK with CTA_FILTER_F_ALL, removing the manual mask checks. - CTA_EXPECT_FLAGS: use NLA_POLICY_MASK with NF_CT_EXPECT_MASK, adding a new mask define grouping all valid expect flags. Extracted from a broader nf-next patch by Florian Westphal, scoped to ctnetlink for the fixes tree.

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 c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before 435b576cd2faa75154777868f8cbb73bf71644d3; from c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before 2ef71307c86a9f866d6e28f1a0c06e2e9d794474; from c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before 4f7d25f3f0786402ba48ff7d13b6241d77d975f5; from c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before fcec5ce2d73a41668b24e3f18c803541602a59f6; from c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before 675c913b940488a84effdeeac5a1cfb657b59804; from c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before c6cb41eaae875501eaaa487b8db6539feb092292; from c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before 45c33e79ae705b7af97e3117672b6cd258dd0b1b; from c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4 before 8f15b5071b4548b0aafc03b366eb45c9c6566704	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 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 2.6.22.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.168; from 6.2 before 6.6.131; from 6.7 before 6.12.80; from 6.13 before 6.18.21; from 6.19 before 6.19.11; 2.6.22; and 7 more ranges	NVD

References

References

https://git.kernel.org/stable/c/435b576cd2faa75154777868f8cbb73bf71644d3	patch
https://git.kernel.org/stable/c/2ef71307c86a9f866d6e28f1a0c06e2e9d794474	patch
https://git.kernel.org/stable/c/4f7d25f3f0786402ba48ff7d13b6241d77d975f5	patch
https://git.kernel.org/stable/c/fcec5ce2d73a41668b24e3f18c803541602a59f6	patch
https://git.kernel.org/stable/c/675c913b940488a84effdeeac5a1cfb657b59804	patch
https://git.kernel.org/stable/c/c6cb41eaae875501eaaa487b8db6539feb092292	patch
https://git.kernel.org/stable/c/45c33e79ae705b7af97e3117672b6cd258dd0b1b	patch
https://git.kernel.org/stable/c/8f15b5071b4548b0aafc03b366eb45c9c6566704	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
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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.