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PatchSiren cyber security CVE debrief

CVE-2026-47331 Canonical CVE debrief

A race condition in Ubuntu's AppArmor SAUCE patches for Linux kernel 6.8 allows unprivileged local users to trigger use-after-free (UAF) conditions. The vulnerability stems from missing lock acquisition during linked list modifications, which could theoretically enable arbitrary code execution with elevated privileges. This affects Ubuntu's kernel packaging and requires local access to exploit.

Vendor
Canonical
Product
Ubuntu Linux
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-05-28
Original CVE updated
2026-05-29
Advisory published
2026-05-28
Advisory updated
2026-05-29

Who should care

Organizations running Ubuntu with Linux kernel 6.8 and AppArmor enabled; multi-tenant environments with untrusted local users; container hosts where container escape via kernel exploitation is a concern

Technical summary

The vulnerability exists in Ubuntu-specific SAUCE (Ubuntu-specific patches applied to upstream kernel) modifications to AppArmor. The affected code path fails to properly synchronize access when modifying linked list structures, creating a window where memory can be freed while still referenced. An unprivileged local attacker with the ability to execute code can trigger this race condition repeatedly to achieve UAF, potentially corrupting kernel memory structures and gaining arbitrary code execution in kernel context. The attack complexity is rated low (AC:L), suggesting reliable exploitation may be feasible.

Defensive priority

HIGH

Recommended defensive actions

  • Apply Ubuntu kernel security updates when available
  • Restrict local user access to trusted personnel only
  • Monitor for anomalous kernel-level activity and privilege escalation attempts
  • Review AppArmor profile configurations for unnecessary permissions
  • Consider enabling kernel lockdown mode where compatible with operational requirements

Evidence notes

Vulnerability confirmed through official Ubuntu kernel commit reference. CVSS 3.1 vector AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H indicates local attack vector with low complexity. CWE-416 (Use After Free) classification aligns with described race condition mechanism. Vendor identification marked low confidence due to 'Unknown Vendor' classification in source data, though Launchpad reference strongly indicates Ubuntu as affected vendor.

Official resources

2026-05-28