CVE-2026-47333

What it actually does

This vulnerability is a local kernel memory-corruption flaw in Ubuntu-specific AppArmor patches affecting Linux kernel lines 6.8, 6.17, and 7.0. AppArmor notification handling can incorrectly calculate the size of an internal heap buffer, causing an out-of-bounds read. Because the malformed data is then processed by the AppArmor DFA policy engine, an unprivileged local user may be able to influence kernel memory handling in a way that can compromise confidentiality, integrity, or availability. The CVSS vector indicates local access is required, exploitation complexity is low, no user interaction is needed, and successful exploitation can have high impact across the system.

Why it matters to the business

A user or process that already has low-privileged local access to an affected Ubuntu system could potentially escalate impact at the operating-system level, disrupt workloads, expose sensitive data in kernel memory, or weaken AppArmor policy enforcement. This is most relevant for multi-user servers, shared compute environments, developer workstations, container hosts, CI runners, and systems where untrusted or semi-trusted users can execute local code. Although EPSS is currently low and there is no known KEV listing or public exploit maturity reported, the high CVSS impact means exposed systems should still be prioritized once vendor fixes or mitigations are available.

How an attack unfolds

An attacker first needs the ability to run code as an unprivileged local user on an affected Ubuntu system using one of the impacted kernel versions with the AppArmor SAUCE patches. The attacker then interacts with AppArmor notification functionality in a way that causes the kernel to miscalculate an internal buffer size. This triggers a heap out-of-bounds read during notification handling, and the resulting invalid data may be fed into the AppArmor DFA policy engine. Depending on kernel layout, hardening, and reachable code paths, exploitation may lead to information disclosure, policy-engine confusion, denial of service, or potentially broader local privilege escalation. There is no current indication from the provided data that this vulnerability is being exploited in the wild or used by ransomware campaigns.

How to fix it

Apply Canonical-provided kernel updates as soon as fixed packages become available for the affected Ubuntu releases and kernel lines. Because no exact fixed versions were provided, track the relevant Ubuntu Security Notice and package changelogs for kernel updates addressing this vulnerability, then reboot systems into the updated kernel. As interim mitigations, restrict local shell access to trusted users, reduce exposure of shared or multi-tenant Linux hosts, isolate untrusted workloads, avoid running untrusted code on affected systems, and consider temporarily disabling or limiting AppArmor notification workflows if operationally feasible and supported. Do not rely on disabling AppArmor broadly as a primary mitigation unless directed by the vendor, because that may reduce overall system confinement.

How to confirm the fix worked

Confirm exposure by inventorying Ubuntu systems and checking the running kernel version with commands such as `uname -r`, then compare against Canonical advisories for this vulnerability and the affected 6.8, 6.17, and 7.0 kernel lines. After patching, verify the updated kernel package is installed and that the system has rebooted into the fixed kernel; merely installing a kernel package is insufficient if the running kernel remains vulnerable. Validate AppArmor is operating normally after the update using standard AppArmor status checks and review kernel logs for new AppArmor, audit, Oops, BUG, KASAN, or general-protection-fault messages. In vulnerability management tooling, mark the issue remediated only when the running kernel version is confirmed fixed, not just when an update is staged.

Typical attack path

1. Obtain local low-privileged code execution on an affected Ubuntu system.
2. Confirm the host is running an affected Ubuntu kernel line, such as 6.8, 6.17, or 7.0, with AppArmor enabled.
3. Trigger AppArmor notification-handling code using crafted local interactions that reach the vulnerable buffer-size calculation.
4. Cause a heap out-of-bounds read in kernel memory.
5. Leverage the invalid data processed by the AppArmor DFA policy engine to attempt information disclosure, policy disruption, denial of service, or privilege escalation.
6. Clean up local artifacts where possible and continue operating with elevated impact if exploitation succeeds.

How to detect it

Detection should focus on signs of attempted local exploitation or kernel instability rather than a single reliable network indicator, because exploitation requires local access and no public exploit indicators are provided. Review kernel logs, system journals, audit logs, and AppArmor logs for crashes, warnings, or abnormal notification activity involving AppArmor. Look for kernel Oops, BUG, KASAN, slab out-of-bounds, general protection fault, or panic messages that mention AppArmor or occur near AppArmor notification events. Correlate any such events with local user sessions, newly created accounts, unusual sudo/su activity, suspicious processes launched by low-privileged users, CI job execution, container workloads, or unexpected AppArmor policy-notification activity. Absence of these logs does not prove non-exploitation, because kernel memory-corruption attempts may fail silently or leave minimal artifacts.

• apparmor
• AppArmor
• audit: type=1400
• BUG: KASAN
• slab-out-of-bounds
• heap out-of-bounds
• general protection fault
• kernel BUG
• Oops:
• Kernel panic
• apparmor="DENIED"
• apparmor="ALLOWED"

What your security team should do

• Prioritize patching shared, multi-user, developer, CI/CD, container-host, and internet-facing systems where attackers may gain low-privileged local code execution through another flaw.
• Track Canonical Ubuntu security notices for exact fixed kernel package versions, since fixed versions were not provided in the input data.
• Inventory systems running Ubuntu kernel lines 6.8, 6.17, and 7.0 and identify where AppArmor is enabled and local untrusted code execution is possible.
• Require reboot validation after kernel updates to ensure systems are actually running the remediated kernel.
• Harden local access paths, including SSH, CI runners, application service accounts, and container escape boundaries, to reduce the chance an attacker can reach the local exploit prerequisite.
• Monitor kernel, audit, and AppArmor logs for crashes or abnormal AppArmor notification behavior, especially on systems with recent suspicious local account activity.
• Because EPSS is currently low, balance emergency response against higher-risk known-exploited issues, but do not defer remediation indefinitely due to the high potential local impact.