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VulnerabilityPublished Updated

CVE-2026-31665: Linux kernel · netfilter: nft_ct: fix use-after-free in timeout object destroy

Affects Linux kernelSource CVE Database V5

0

Not known to be exploited · CVSS 7.8 High · fixed in f16fe84879a5280f05ebbcea593a189ba0f3e79a : patch Linux kernel soon.

Data as of 26 Oct 2026, 14:18 UTC

CVSS 3.1 base score
7.8High
How severe the flaw is on the 0–10 CVSS scale.
EPSS
0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
CISA SSVC
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
Total control over the software or total information disclosure

CISA SSVC assessment, 2026-10-16.

Patch
Available – fixed in f16fe84879a5280f05ebbcea593a189ba0f3e79a, f8dca15a1b190787bbd03285304b569631160eda, d0983b48c10d1509fd795c155f8b1e832e1369ff +5
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 24 Apr 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
LinuxLinuxAffected
  • ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < f16fe84879a5280f05ebbcea593a189ba0f3e79a
Fixed in
  • f16fe84879a5280f05ebbcea593a189ba0f3e79a
LinuxLinuxAffected
  • ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < f8dca15a1b190787bbd03285304b569631160eda
Fixed in
  • f8dca15a1b190787bbd03285304b569631160eda
LinuxLinuxAffected
  • ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < d0983b48c10d1509fd795c155f8b1e832e1369ff
Fixed in
  • d0983b48c10d1509fd795c155f8b1e832e1369ff
LinuxLinuxAffected
  • ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < c581e5c8f2b59158f62efe61c1a3dc36189081ff
Fixed in
  • c581e5c8f2b59158f62efe61c1a3dc36189081ff
LinuxLinuxAffected
  • ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < c458fc1c278a65ad5381083121d39a479973ebed
Fixed in
  • c458fc1c278a65ad5381083121d39a479973ebed
LinuxLinuxAffected
  • ≥ 7e0b2b57f01d183e1c84114f1f2287737358d748, < b42aca3660dc2627a29a38131597ca610dc451f9
Fixed in
  • b42aca3660dc2627a29a38131597ca610dc451f9

AI-suggested

A fix is available and has been applied in specific Linux kernel commits identified by their hashes. Users should update their Linux kernel to a version that includes these fixes to mitigate this vulnerability. No additional mitigation steps are indicated by the vendor advisory.

Description

CVE-2026-31665 is a use-after-free vulnerability in the Linux kernel's netfilter nft_ct module related to improper handling of timeout object destruction. The flaw occurs because the timeout object is freed immediately after untimeout without waiting for an RCU grace period, potentially allowing concurrent CPUs to access freed memory. This issue has been fixed by deferring the free operation until after the RCU grace period using kfree_rcu().

References

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