VulnerabilityPublished 17 Sep 2026Updated 30 Oct 2026

CVE-2026-90061: Linux kernel · netfilter: nf_tables: skip double clone set expressions on element insert

Source GCVE Database

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Authoritative record:CVE-2026-90061· Low

Not known to be exploited · fixed in c6b56b8d549a043b6c8ff616db8748263eae05ae : update Linux kernel when convenient.

Data as of 30 Oct 2026, 19:18 UTC

Severity

Low

Rated Low by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in c6b56b8d549a043b6c8ff616db8748263eae05ae, 43559058d21e0493aa220ac167e0279334dea5f9, 109bf28a90ac365ec4d25622c50959bb43b35ed4 +3

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Sep 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 30 Oct 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.

ghsa-gc4j-f8fc-95gw

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ 65038428b2c6c5be79d3f78a6b79c0cdc3a58a41, < c6b56b8d549a043b6c8ff616db8748263eae05ae	Fixed in c6b56b8d549a043b6c8ff616db8748263eae05ae
LinuxLinux	Affected ≥ 65038428b2c6c5be79d3f78a6b79c0cdc3a58a41, < 43559058d21e0493aa220ac167e0279334dea5f9	Fixed in 43559058d21e0493aa220ac167e0279334dea5f9
LinuxLinux	Affected ≥ 65038428b2c6c5be79d3f78a6b79c0cdc3a58a41, < 109bf28a90ac365ec4d25622c50959bb43b35ed4	Fixed in 109bf28a90ac365ec4d25622c50959bb43b35ed4
LinuxLinux	Affected ≥ 65038428b2c6c5be79d3f78a6b79c0cdc3a58a41, < 9cbf6da967ec8c6e8278b70353b712980a12d848	Fixed in 9cbf6da967ec8c6e8278b70353b712980a12d848
LinuxLinux	Affected ≥ 65038428b2c6c5be79d3f78a6b79c0cdc3a58a41, < 04d1930072e694d9d03bfefdb7e1ebdc872a3d0c	Fixed in 04d1930072e694d9d03bfefdb7e1ebdc872a3d0c
LinuxLinux	Affected ≥ 65038428b2c6c5be79d3f78a6b79c0cdc3a58a41, < 1e7fb6801d9cc826adcdb7fa0533c397730657f2	Fixed in 1e7fb6801d9cc826adcdb7fa0533c397730657f2

AI-suggested

A fix has been implemented in the Linux kernel to address this issue by correcting the cloning logic and managing expression references properly. Users should update to the fixed kernel version once available. Patch status is not explicitly confirmed in the provided data; users should consult the official Linux kernel advisories for the exact fixed versions and apply updates accordingly.

Description

A vulnerability in the Linux kernel's netfilter nf_tables subsystem involved double cloning of set expressions when inserting elements. This flaw caused a module reference count imbalance warning related to the connlimit expression. The issue was resolved by improving the cloning logic to avoid redundant cloning and properly manage expression references.

Impact

The vulnerability caused a module reference count imbalance warning in the kernel, which could lead to instability or unexpected behavior in the netfilter nf_tables subsystem. There is no indication of remote code execution or privilege escalation. No known exploits in the wild have been reported.

Summary

The Linux kernel netfilter nf_tables component had a bug where both the dynset and newsetelem paths cloned existing set expressions redundantly when no override expressions were provided. This double cloning led to a module reference count imbalance warning, particularly affecting the connlimit expression. The fix introduced a flag to indicate when userspace provides an override expression, allowing the system to borrow existing expressions instead of cloning them twice. Additional conditionals were added to correctly release expressions only if they represent overrides, simplifying the logic and preventing the reference count imbalance.

References

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