CVE-2026-23404: Linux kernel · apparmor: replace recursive profile removal with iterative approach
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 4.15.0-1200.215~14.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 12:55 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 7% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 4.15.0-1200.215~14.04.1, 4.15.0-1191.204~16.04.1, 4.15.0-1200.215~16.04.1 +108
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 1 Apr 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.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux@6.17.0-19.19?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws@6.17.0-1009.9?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure@6.17.0-1010.10?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde@6.17.0-1017.17?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp@6.17.0-1009.9?arch=source&distro=questingOther threats | Affected
| Fixed in
|
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle@6.17.0-1009.9?arch=source&distro=questingOther threats | Affected
| 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 patch is available and has been released by the Linux kernel maintainers and distributors such as Ubuntu. Users should apply the official kernel updates that include the fix replacing recursive profile removal with an iterative approach. No additional mitigation actions are required beyond applying the vendor-provided patch.
Description
A vulnerability in the Linux kernel's AppArmor security module involved recursive profile removal, which could exhaust the kernel stack and cause system crashes. The issue was addressed by replacing the recursive removal method with an iterative approach. This flaw affected specific Linux kernel versions and could be exploited by a local attacker to cause denial of service. The vulnerability has a medium severity rating and a CVSS score of 5.5. A patch is available and has been released by the vendor.
References
- ubuntu.com/security/CVE-2026-23404 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23404 (opens in a new tab)
- ubuntu.com/blog/apparmor-vulnerability-fixes-available (opens in a new tab)
- ubuntu.com/security/vulnerabilities/crackarmor (opens in a new tab)
- cdn2.qualys.com/advisory/2026/03/10/crack-armor.txt (opens in a new tab)
- openwall.com/lists/oss-security/2026/04/01/3 (opens in a new tab)
- ubuntu.com/security/notices/USN-8152-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8163-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8164-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8165-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8163-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8098-10 (opens in a new tab)
- ubuntu.com/security/notices/USN-8201-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8224-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8243-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8261-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8266-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8267-1 (opens in a new tab)