VulnerabilityPublished 17 Sep 2026Updated 17 Oct 2026

CVE-2026-90179: Linux kernel · apparmor: fix deadlock in complain-mode change_hat

Affects Linux kernelSource GCVE Database

Authoritative record:CVE-2026-90179

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 restructures locking in the AppArmor change_hat code and corrects related reference counting bugs. Users should apply the official kernel updates that include this fix. Since this is a kernel-level issue, upgrading to patched kernel versions is the recommended remediation. Patch status is not explicitly confirmed in the provided data; therefore, check the vendor advisory for the latest remediation guidance.

Description

A deadlock vulnerability in the Linux kernel's AppArmor component was fixed. The issue occurs when using change_hat in complain mode, causing the system to hang and become unresponsive due to a locking deadlock when creating a new learning profile. This affects certain Linux kernel versions and leads to processes becoming unkillable and stuck. The problem was identified in Ubuntu 26.04 LTS and various vanilla kernel versions. The fix involves restructuring locking mechanisms and correcting reference count leaks introduced by a previous commit.

Impact

Processes invoking change_hat() in complain mode on affected kernels may hang indefinitely due to a deadlock, becoming unkillable and causing system instability related to AppArmor profile management. This can block further hat changes and potentially disrupt normal operation of security confinement mechanisms relying on AppArmor.

Summary

The vulnerability in the Linux kernel's AppArmor module involves a deadlock triggered by the use of change_hat() in complain mode when the hat does not exist and a new learning profile must be created. The deadlock arises because change_hat() holds a lock while searching the hat list, and creating the new learning profile requires taking the same lock, causing the process to hang indefinitely. This was observed in Ubuntu 26.04 LTS kernel 7.0.0 and verified in vanilla kernels 7.2-rc7 and 6.18.44, but not in 6.12.95 with Debian patches. The deadlock causes the affected process to become unkillable and blocks further hat changes. The fix involved lifting the locking out of the core profile creation function, introducing a wrapper to manage locking, and correcting four additional issues related to reference counting and potential use-after-free conditions introduced by a prior commit.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 24 Oct 2026, 21:52 UTC

Technical details

References

Community reviews

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