Bug 2453796 (CVE-2026-23403)

Summary: CVE-2026-23403 kernel: apparmor: fix memory leak in verify_header
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
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Version: unspecifiedKeywords: Security
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OS: Linux   
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A flaw was found in AppArmor within the Linux kernel. This vulnerability, located in the verify_header function, causes a memory leak by incorrectly handling namespace strings when multiple security profiles are processed. This can lead to a gradual depletion of system memory, potentially impacting system stability and the integrity of security policy enforcement.
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Description OSIDB Bzimport 2026-04-01 10:02:12 UTC 
In the Linux kernel, the following vulnerability has been resolved:

apparmor: fix memory leak in verify_header

The function sets `*ns = NULL` on every call, leaking the namespace
string allocated in previous iterations when multiple profiles are
unpacked. This also breaks namespace consistency checking since *ns
is always NULL when the comparison is made.

Remove the incorrect assignment.
The caller (aa_unpack) initializes *ns to NULL once before the loop,
which is sufficient.
Comment 1 Alexander B 2026-04-01 13:35:44 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026040111-CVE-2026-23403-f22c@gregkh/T