CVE-2026-23405

Local service interruption via unbounded policy namespace nesting

Published Apr 1, 2026 · Updated Apr 1, 2026

Resource exhaustion in Linux Kernel AppArmor allows local users to interrupt service by creating deeply nested policy namespaces. The __aa_create_ns function allocates each child namespace without checking its parent depth, allowing nesting beyond the user-namespace limit. Local access and permission to create AppArmor policy namespaces are required; repeated nesting consumes kernel resources and degrades availability.

CVSS severity5.5
Medium
EPSS probability0.18%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Resource exhaustion in Linux Kernel AppArmor allows local users to interrupt service by creating deeply nested policy namespaces. The __aa_create_ns function allocates each child namespace without checking its parent depth, allowing nesting beyond the user-namespace limit. Local access and permission to create AppArmor policy namespaces are required; repeated nesting consumes kernel resources and degrades availability.

The record

CVE
CVE-2026-23405
Published
Apr 1, 2026
Updated
Apr 1, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
T1499.004
Attack vector
local
Privileges
authenticated

Timeline

How it unfolded

  1. Apr 1, 2026CVE publishedPublication date reported by the CVE source.
  2. Apr 1, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2.6.36
  2. Affected versionversion=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <306039414932c80f8420695a24d4fe10c84ccfb2
  3. Affected versionversion=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <3f8699b3ee0c04b4b9bc27b82cd89a40e81e1d2e
  4. Affected versionversion=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <7b6495ead2c611647f6b11441a852324e3eb8616
  5. Affected versionversion=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <853ce31ca72097d23991a06876a2ccb5cb64b603
  6. Affected versionversion=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <d42b2b6bb77ca40ee34ab74ad79305840b5f315d

What conditions does exploitation require?

Attack vectorlocal
Required privilegesauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=2.6.36; version=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <306039414932c80f8420695a24d4fe10c84ccfb2; version=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <3f8699b3ee0c04b4b9bc27b82cd89a40e81e1d2e; version=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <7b6495ead2c611647f6b11441a852324e3eb8616; version=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <853ce31ca72097d23991a06876a2ccb5cb64b603; version=c88d4c7b049e87998ac0a9f455aa545cc895ef92 <d42b2b6bb77ca40ee34ab74ad79305840b5f315d

Published CVSS scores

5.5NVDCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorlocal
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

T1499.004Application or System Exploitation

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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