CVE-2026-31665: Linux kernel · netfilter: nft_ct: fix use-after-free in timeout object destroy
Affects Linux kernelSource CVE Database V5
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
- 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:HExploitation evidence
Disclosed: evidence found.
CVE published 24 Apr 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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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
- git.kernel.org/stable/c/c458fc1c278a65ad5381083121d39a479973ebed (opens in a new tab)
- git.kernel.org/stable/c/c581e5c8f2b59158f62efe61c1a3dc36189081ff (opens in a new tab)
- git.kernel.org/stable/c/f16fe84879a5280f05ebbcea593a189ba0f3e79a (opens in a new tab)
- git.kernel.org/stable/c/070abdf1b04325b21a20a2a0c39a2208af107275 (opens in a new tab)
- git.kernel.org/stable/c/aa7cfa16f98f8ec3e6d47c34e1a8c1ae4b9b8b77 (opens in a new tab)
- git.kernel.org/stable/c/b42aca3660dc2627a29a38131597ca610dc451f9 (opens in a new tab)
- git.kernel.org/stable/c/d0983b48c10d1509fd795c155f8b1e832e1369ff (opens in a new tab)
- git.kernel.org/stable/c/f8dca15a1b190787bbd03285304b569631160eda (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)