VulnerabilityPublished 4 Sep 2025Updated 5 Nov 2026

CVE-2025-38721: Linux kernel · netfilter: ctnetlink: fix refcount leak on table dump

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in e14f72aa66c029db106921d621edcedef68e065b : update Linux kernel when convenient.

Data as of 5 Nov 2026, 21:34 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 e14f72aa66c029db106921d621edcedef68e065b, de788b2e6227462b6dcd0e07474e72c089008f74, a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b +6

Exploitation evidence

Disclosed: evidence found.
CVE published 4 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.

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 ≥ d205dc40798d97d63ad348bfaf7394f445d152d4, < e14f72aa66c029db106921d621edcedef68e065b	Fixed in e14f72aa66c029db106921d621edcedef68e065b
LinuxLinux	Affected ≥ d205dc40798d97d63ad348bfaf7394f445d152d4, < de788b2e6227462b6dcd0e07474e72c089008f74	Fixed in de788b2e6227462b6dcd0e07474e72c089008f74
LinuxLinux	Affected ≥ d205dc40798d97d63ad348bfaf7394f445d152d4, < a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b	Fixed in a62d6aa3f31f216b637a4c71b7a8bfc7c57f049b
LinuxLinux	Affected ≥ d205dc40798d97d63ad348bfaf7394f445d152d4, < a2cb4df7872de069f809de2f076ec8e54d649fe3	Fixed in a2cb4df7872de069f809de2f076ec8e54d649fe3
LinuxLinux	Affected ≥ d205dc40798d97d63ad348bfaf7394f445d152d4, < 962518c6ca9f9a13df099cafa429f72f68ad61f0	Fixed in 962518c6ca9f9a13df099cafa429f72f68ad61f0
LinuxLinux	Affected ≥ d205dc40798d97d63ad348bfaf7394f445d152d4, < 586892e341fbf698e7cbaca293e1353957db725a	Fixed in 586892e341fbf698e7cbaca293e1353957db725a

Description

In the Linux kernel, the following vulnerability has been resolved: netfilter: ctnetlink: fix refcount leak on table dump There is a reference count leak in ctnetlink_dump_table(): if (res < 0) { nf_conntrack_get(&ct->ct_general); // HERE cb->args[1] = (unsigned long)ct; ... While its very unlikely, its possible that ct == last. If this happens, then the refcount of ct was already incremented. This 2nd increment is never undone. This prevents the conntrack object from being released, which in turn keeps prevents cnet->count from dropping back to 0. This will then block the netns dismantle (or conntrack rmmod) as nf_conntrack_cleanup_net_list() will wait forever. This can be reproduced by running conntrack_resize.sh selftest in a loop. It takes ~20 minutes for me on a preemptible kernel on average before I see a runaway kworker spinning in nf_conntrack_cleanup_net_list. One fix would to change this to: if (res < 0) { if (ct != last) nf_conntrack_get(&ct->ct_general); But this reference counting isn't needed in the first place. We can just store a cookie value instead. A followup patch will do the same for ctnetlink_exp_dump_table, it looks to me as if this has the same problem and like ctnetlink_dump_table, we only need a 'skip hint', not the actual object so we can apply the same cookie strategy there as well.

References

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