VulnerabilityPublished 17 Sep 2026Updated 5 Oct 2026

CVE-2026-90232: Linux kernel · amt: Don't support cross-netns setup.

Affects Linux kernelSource GCVE Database

Authoritative record:CVE-2026-90232

Not known to be exploited.

Data as of 26 Oct 2026, 14:05 UTC

Severity

Medium

Rated by Threat Radar · CVSS not yet scored by NVD

EPSS: 0.2% chance of exploitation in 30 days – higher than 10% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.

Exploitation evidence

Disclosed: evidence found.
CVE published 17 Sep 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.

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.
Weaponised: Public exploit code exists in Metasploit or Exploit-DB, 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

Affected software

Product	Affected	Fixed in
Ubuntu 26.04 LTSlinux`pkg:deb/ubuntu/linux?arch=source&distro=resolute`Other threats	Affected 6.17.0-5.5 – 7.0.0-38.38 23 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-aws`pkg:deb/ubuntu/linux-aws?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure`pkg:deb/ubuntu/linux-azure?arch=source&distro=resolute`Other threats	Affected 6.17.0-1003.3 – 7.0.0-1017.17 15 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-azure-fde`pkg:deb/ubuntu/linux-azure-fde?arch=source&distro=resolute`Other threats	Affected 7.0.0-1003.3 – 7.0.0-1016.16 9 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gcp`pkg:deb/ubuntu/linux-gcp?arch=source&distro=resolute`Other threats	Affected 6.17.0-1002.2 – 7.0.0-1014.14 13 affected builds	Fixed in–
Ubuntu 26.04 LTSlinux-gke`pkg:deb/ubuntu/linux-gke?arch=source&distro=resolute`Other threats	Affected 7.0.0-1002.3 – 7.0.0-1008.9 6 affected builds	Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix has been implemented that forbids cross-network namespace setups for AMT devices, preventing the problematic condition. Users should update to Linux kernel versions that include this fix. Since this is a kernel-level fix, upgrading the kernel package to a patched version is the recommended remediation. No additional mitigations are indicated.

Description

A vulnerability in the Linux kernel's AMT (Alternate MAC/PHY Transport) device handling has been resolved. The flaw involves improper support for cross-network namespace (netns) setups, where unregistering a lower device can cause the system to hang due to incomplete cleanup of upper AMT devices. The vulnerability arises because the code only looks up upper devices in the lower device's netns and unregisters only a single upper device, leading to a deadlock when devices span multiple net namespaces. The fix forbids cross-netns setups rather than supporting them properly.

Impact

The vulnerability can cause the Linux kernel to hang (deadlock) during network device unregistration when AMT devices are configured across different network namespaces. This can lead to system instability or denial of service conditions affecting network functionality. There is no indication of remote code execution or privilege escalation from the provided data.

Summary

The Linux kernel vulnerability (CVE-2026-90232) affects the AMT device driver, which mishandles device unregistration in cross-network namespace scenarios. Specifically, amt_device_event() attempts to unregister an upper AMT device when a lower device is unregistered, but amt_lookup_upper_dev() only searches within the lower device's netns, and amt_device_event() unregisters only one upper device. This causes a deadlock if the AMT device is created on a lower device in a different netns, resulting in the kernel getting stuck until all upper devices are removed. The cross-netns setup appears unintentional, as indicated by the immutable netns flag and failure of iproute2 to create such links. The fix implemented forbids cross-netns setups to prevent this issue.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Oct 2026, 22:06 UTC

Technical details

References

Community reviews

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