CVE-2026-47336

What it actually does

This vulnerability affects Ubuntu Linux 6.8 kernels that include Ubuntu-specific AppArmor SAUCE patches for AF_INET and AF_INET6 socket mediation. A local unprivileged user can trigger a code path where an uninitialized variable may be used during AppArmor network socket policy enforcement. The likely result is incorrect fine-grained mediation of IPv4 or IPv6 socket operations, potentially allowing network actions to be permitted or denied inconsistently with the intended AppArmor profile. The CVSS impact is limited to low integrity impact, with no direct confidentiality or availability impact indicated.

Why it matters to the business

An attacker who already has local access to an affected Ubuntu system may be able to bypass parts of AppArmor network socket restrictions, weakening isolation controls for confined applications or users. This is most relevant on multi-user systems, shared development hosts, container-adjacent workloads relying on AppArmor policy, and environments where AppArmor is used as a compensating control to limit outbound or inbound network behavior. The issue is not known to be exploited in the wild, is not listed in CISA KEV, and has very low EPSS likelihood, so remediation should be handled through normal kernel patch management unless the affected systems rely heavily on AppArmor network confinement.

How an attack unfolds

Exploitation requires local access with the ability to execute code as an unprivileged user. The attacker runs a program that creates or manipulates IPv4 or IPv6 sockets in a way that reaches the vulnerable AppArmor mediation path in the Ubuntu 6.8 kernel. Because the mediation logic may consume an uninitialized variable, the AppArmor decision for the socket operation can become incorrect. In a practical scenario, the attacker would attempt repeated socket operations from within a confined context to determine whether policy-restricted network behavior is unexpectedly allowed. Successful exploitation would not normally provide root privileges or direct code execution in the kernel, but it could undermine network restrictions that AppArmor profiles are expected to enforce.

How to fix it

Apply the Ubuntu kernel update that corrects the AppArmor AF_INET/AF_INET6 socket mediation logic once available through Canonical security repositories. Because no exact fixed package versions were provided, use the distribution security advisory and package manager metadata as the source of truth for the corrected kernel version. After updating, reboot into the patched kernel and remove or de-prioritize vulnerable kernels from boot options where operationally feasible. As interim mitigation, reduce local shell access to affected systems, avoid relying solely on AppArmor network mediation for high-risk boundaries, review AppArmor profiles that use fine-grained network socket controls, and consider additional network-layer controls such as host firewall rules, egress filtering, or service-level access controls.

How to confirm the fix worked

Confirm exposure by checking whether the system is Ubuntu Linux running a 6.8-series kernel containing the affected AppArmor patches and whether AppArmor is enabled. Validate remediation by confirming the installed and running kernel version matches the patched Ubuntu security update, then rebooting if the updated kernel is installed but not active. Verify AppArmor remains enabled and profiles are loaded after reboot. Where AppArmor network policy is relied upon, perform a controlled negative test from a confined profile to ensure restricted IPv4 and IPv6 socket operations are denied as expected.

Typical attack path

1. Gain local unprivileged access to an affected Ubuntu Linux system running a vulnerable 6.8 kernel.
2. Identify whether AppArmor is enabled and whether the current process is subject to a profile with network socket restrictions.
3. Run crafted IPv4 or IPv6 socket operations that exercise AppArmor AF_INET or AF_INET6 socket mediation.
4. Observe whether network operations that should be blocked by policy are inconsistently allowed.
5. Use any bypassed network permission to communicate with restricted local or remote services, depending on the AppArmor policy design.

How to detect it

There are no public, reliable, CVE-specific indicators of exploitation for this issue. Detection should focus on signs that a local user or confined process attempted unusual IPv4 or IPv6 socket activity that conflicts with AppArmor policy expectations. Review auditd, kernel logs, AppArmor logs, process execution telemetry, and EDR events for confined processes making repeated or unexpected socket calls, especially where AppArmor denials are absent despite policy expectations. Useful log sources include /var/log/audit/audit.log, journalctl kernel messages, /var/log/kern.log, /var/log/syslog, AppArmor parser/status output, process accounting, and network connection telemetry. Investigate unexpected outbound connections or listeners created by applications that should be AppArmor-confined from such network behavior. Because the flaw may result in incorrect mediation rather than a distinctive crash or artifact, absence of AppArmor denial logs does not prove absence of exploitation.

What your security team should do

• Inventory Ubuntu systems running Linux 6.8 kernels and prioritize those that permit local user execution, shared access, CI/CD workloads, or untrusted code execution.
• Monitor Canonical Ubuntu Security Notices and kernel package updates for the fixed version, then apply the patched kernel through standard maintenance channels.
• Prioritize faster remediation for systems where AppArmor profiles are used to enforce network isolation boundaries.
• Reboot systems after kernel updates and verify the patched kernel is the active running kernel.
• Restrict unnecessary local user access and untrusted code execution until affected systems are patched.
• Use host firewall or network policy controls as defense-in-depth for any AppArmor-enforced network restrictions.
• Do not treat this as an internet-exposed remote compromise risk based on currently available information; exploitation requires local access.