VulnerabilityPublished 22 Apr 2026Updated 5 Nov 2026

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

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in fcec5ce2d73a41668b24e3f18c803541602a59f6 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 22:19 UTC

Severity

Unrated

Rated by Threat Radar · No CVSS score from NVD or the CNA

Thin evidence

One scorer or none

Exploitation: No evidence of active exploitation and no public proof of concept
Automatable: Attackers cannot reliably automate steps 1–4 of the kill chain
Technical impact: Limited control over the software or limited information exposure

CISA SSVC assessment, 2026-11-05.

Patch

Available – fixed in fcec5ce2d73a41668b24e3f18c803541602a59f6, c6cb41eaae875501eaaa487b8db6539feb092292, 675c913b940488a84effdeeac5a1cfb657b59804 +5

Exploitation evidence

Disclosed: evidence found.
CVE published 22 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4, < fcec5ce2d73a41668b24e3f18c803541602a59f6	Fixed in fcec5ce2d73a41668b24e3f18c803541602a59f6
LinuxLinux	Affected ≥ c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4, < c6cb41eaae875501eaaa487b8db6539feb092292	Fixed in c6cb41eaae875501eaaa487b8db6539feb092292
LinuxLinux	Affected ≥ c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4, < 675c913b940488a84effdeeac5a1cfb657b59804	Fixed in 675c913b940488a84effdeeac5a1cfb657b59804
LinuxLinux	Affected ≥ c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4, < 435b576cd2faa75154777868f8cbb73bf71644d3	Fixed in 435b576cd2faa75154777868f8cbb73bf71644d3
LinuxLinux	Affected ≥ c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4, < 45c33e79ae705b7af97e3117672b6cd258dd0b1b	Fixed in 45c33e79ae705b7af97e3117672b6cd258dd0b1b
LinuxLinux	Affected ≥ c8e2078cfe414a99cf6f2f2f1d78c7e75392e9d4, < 8f15b5071b4548b0aafc03b366eb45c9c6566704	Fixed in 8f15b5071b4548b0aafc03b366eb45c9c6566704

AI-suggested

A fix for this vulnerability has been applied in the Linux kernel as indicated by multiple fixed commit versions. Users and administrators should update their Linux kernel to a version that includes these fixes to ensure the vulnerability is remediated. No additional mitigation steps are indicated or required beyond applying the official fix.

Description

CVE-2026-31495 addresses a vulnerability in the Linux kernel's netfilter ctnetlink component where manual range and mask validations were replaced with netlink policy range checks. This change ensures that invalid netlink attribute values are rejected early by the netlink core, preventing undefined behavior caused by out-of-range values in TCP state and window scale parameters, as well as filter and expect flags.

Impact

By enforcing strict netlink policy range checks, this fix prevents the acceptance of invalid netlink attribute values that could lead to undefined behavior in kernel networking code. Although the exact impact of the vulnerability is not detailed, the undefined behavior caused by out-of-range TCP window scale values and improper flag masks could potentially lead to kernel instability or security issues. No known exploits in the wild have been reported.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 5 Nov 2026, 22:18 UTC

Technical details

References

Community reviews

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