CVE-2025-39764: Linux kernel · netfilter: ctnetlink: remove refcounting in expectation dumpers
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in bada48ad5b0590e318d0f79636ff62a2ef9f4955 : update Linux kernel when convenient.
Data as of 5 Nov 2026, 21:36 UTC
Rated Medium by Threat Radar's AI analysis · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- 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
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-05.
- Patch
- Available – fixed in bada48ad5b0590e318d0f79636ff62a2ef9f4955, b05500444b8eb97644efdd180839a04a706be97c, a4d634ded4d3d400f115d84f654f316f249531c9 +4
Exploitation evidence
Disclosed: evidence found.
CVE published 11 Sep 2025
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.
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 the Linux kernel source code as indicated by the fixed commit hashes. Users and administrators should update to a Linux kernel version that includes these fixes to remediate the vulnerability.
Description
CVE-2025-39764 is a vulnerability in the Linux kernel's netfilter ctnetlink subsystem related to improper reference counting in expectation dumpers. The flaw involves a double increment of the reference count leading to a memory leak. The issue was resolved by removing refcounting and instead using a cookie value as a skip hint for dump resumption.
References
- git.kernel.org/stable/c/b05500444b8eb97644efdd180839a04a706be97c (opens in a new tab)
- git.kernel.org/stable/c/bada48ad5b0590e318d0f79636ff62a2ef9f4955 (opens in a new tab)
- git.kernel.org/stable/c/64b7684042246e3238464c66894e30ba30c7e851 (opens in a new tab)
- git.kernel.org/stable/c/9e5021a906532ca16e2aac69c0607711e1c70b1f (opens in a new tab)
- git.kernel.org/stable/c/078d33c95bf534d37aa04269d1ae6158e20082d5 (opens in a new tab)
- git.kernel.org/stable/c/a4d634ded4d3d400f115d84f654f316f249531c9 (opens in a new tab)
- git.kernel.org/stable/c/1492e3dcb2be3aa46d1963da96aa9593e4e4db5a (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)