CVE-2026-23405
Received Received - Intake
Resource Exhaustion via Unbounded AppArmor Policy Namespace Nesting

Publication date: 2026-04-01

Last updated on: 2026-04-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: apparmor: fix: limit the number of levels of policy namespaces Currently the number of policy namespaces is not bounded relying on the user namespace limit. However policy namespaces aren't strictly tied to user namespaces and it is possible to create them and nest them arbitrarily deep which can be used to exhaust system resource. Hard cap policy namespaces to the same depth as user namespaces.
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Meta Information
Published
2026-04-01
Last Modified
2026-04-24
Generated
2026-06-16
AI Q&A
2026-04-01
EPSS Evaluated
2026-06-15
NVD
CVE-2026-23405
EUVD
EUVD-2026-17833
Affected Vendors & Products
Showing 15 associated CPEs
Vendor Product Version / Range
linux linux_kernel 2.6.36
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel 7.0
linux linux_kernel From 6.2 (inc) to 6.6.130 (exc)
linux linux_kernel From 6.7 (inc) to 6.12.77 (exc)
linux linux_kernel From 5.11 (inc) to 5.15.203 (exc)
linux linux_kernel From 5.16 (inc) to 6.1.169 (exc)
linux linux_kernel From 6.13 (inc) to 6.18.18 (exc)
linux linux_kernel From 6.19 (inc) to 6.19.8 (exc)
linux linux_kernel From 2.6.36.1 (inc) to 5.10.253 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-UNKNOWN
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Impact Analysis

The vulnerability can lead to resource exhaustion on the affected system. By creating and nesting policy namespaces without limit, an attacker can consume excessive system resources, which may degrade system performance or cause denial of service conditions.

Executive Summary

This vulnerability exists in the Linux kernel's AppArmor component, where the number of policy namespaces is not properly limited. Although policy namespaces are intended to be limited by the user namespace limit, they are not strictly tied to user namespaces and can be created and nested arbitrarily deep. This lack of bounding allows an attacker to create many nested policy namespaces, potentially exhausting system resources.

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