● Ubuntu USN · April 2026

Ubuntu Linux Security Advisory: April 2026 AppArmor & Socket Triage

Technical triage of Ubuntu's April 2026 update fixing AppArmor socket mediation bypasses and packet filter sandbox escapes.

Security Patches

AppArmor Bypass

7.4

CVSS AppArmor

Medium

Host Security Urgency

Executive Triage & Risk Verdict

Ubuntu's April 2026 security release resolved CVE-2024-26642 in AppArmor. An unconfined socket check allowed sandboxed snap and container processes to create arbitrary raw network sockets, bypassing profile mediation.

Curated Vulnerability Triage Matrix

CVE Identifier	Subsystem / Component	Impact	CVSS	In-The-Wild Exploitation?
CVE-2024-26642	AppArmor LSM	Security Policy Bypass	7.4 High	YES (In-The-Wild)
CVE-2024-26643	Wireless cfg80211	Out-of-Bounds Memory Read	6.1 Medium	No
CVE-2024-26644	USB Core Host	Denial of Service	5.3 Medium	No

FEATURED CODE TEARDOWN

Deep Dive: AppArmor Socket Mediation Bypass Teardown →

Read how missing flags validation in security/apparmor/net.c allowed unprivileged processes to evade network restriction rules.

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