CVE-2026-31495
What it is
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.
At a glance
- Exploitability
- Can be exploited locally on the machine with a low-privilege account. High risk of service disruption.
- Exploit odds
- 0.1% chance of exploitation in the next 30 days (EPSS).
- Fix
- A patch, advisory or fixed version is referenced. Upgrade or apply it.
Timeline
- PublishedDisclosed publicly on CVE.org and NVD
- Last updatedMost recent change to the record
Why it ranks here
- Exploited in the wild: no, CISA does not list it.
- Exploit odds: 0.1% in the next 30 days (EPSS).
- Severity: 5.5 MEDIUM (CVSS).
- Fix: a patch or advisory is linked.
Details
- Published
- Last modified
- Exploit probability
- 0.1% · EPSS, next 30 days
- Record status
- Modified
Affected
- Linux Kernel < 5.10.253
- Linux Kernel < 5.15.203
- Linux Kernel < 6.1.168
- Linux Kernel < 6.6.131
- Linux Kernel < 6.12.80
- Linux Kernel < 6.18.21
- Linux Kernel < 6.19.11
- Linux Kernel 2.6.22
Attack profile CVSS 3.1 · 5.5
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Raw vector
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Is it in your code?
Hand this to your coding agent. It searches your project for the affected products and checks versions. Nothing leaves your machine.
Read https://cve-list.com/agent/cve/CVE-2026-31495.md and follow it. Check whether this project is affected by CVE-2026-31495. Read only. Don't change anything and don't upload my code. Tell me yes, no or not sure, with the file as proof.
Fix and advisories
- https://git.kernel.org/stable/c/2ef71307c86a9f866d6e28f1a0c06e2e9d794474
- https://git.kernel.org/stable/c/435b576cd2faa75154777868f8cbb73bf71644d3
- https://git.kernel.org/stable/c/45c33e79ae705b7af97e3117672b6cd258dd0b1b
- https://git.kernel.org/stable/c/4f7d25f3f0786402ba48ff7d13b6241d77d975f5
- https://git.kernel.org/stable/c/675c913b940488a84effdeeac5a1cfb657b59804
- https://git.kernel.org/stable/c/8f15b5071b4548b0aafc03b366eb45c9c6566704
- https://git.kernel.org/stable/c/c6cb41eaae875501eaaa487b8db6539feb092292
- https://git.kernel.org/stable/c/fcec5ce2d73a41668b24e3f18c803541602a59f6
References
- https://git.kernel.org/stable/c/2ef71307c86a9f866d6e28f1a0c06e2e9d794474
- https://git.kernel.org/stable/c/435b576cd2faa75154777868f8cbb73bf71644d3
- https://git.kernel.org/stable/c/45c33e79ae705b7af97e3117672b6cd258dd0b1b
- https://git.kernel.org/stable/c/4f7d25f3f0786402ba48ff7d13b6241d77d975f5
- https://git.kernel.org/stable/c/675c913b940488a84effdeeac5a1cfb657b59804
- https://git.kernel.org/stable/c/8f15b5071b4548b0aafc03b366eb45c9c6566704
- https://git.kernel.org/stable/c/c6cb41eaae875501eaaa487b8db6539feb092292
- https://git.kernel.org/stable/c/fcec5ce2d73a41668b24e3f18c803541602a59f6
- https://cert-portal.siemens.com/productcert/html/ssa-019113.html
- https://cert-portal.siemens.com/productcert/html/ssa-082556.html
- https://cert-portal.siemens.com/productcert/html/ssa-457936.html