CVE-2026-6369: Canonical Livepatch Auth Bypass Vulnerability

CVE-2026-6369 Overview

An improper access control vulnerability exists in the canonical-livepatch snap client prior to version 10.15.0. This security flaw allows a local unprivileged user to obtain a sensitive, root-level authentication token by sending an unauthenticated request to the livepatchd.sock Unix domain socket. The vulnerability is exploitable on systems where an administrator has already enabled the Livepatch client with a valid Ubuntu Pro subscription.

Critical Impact

Successful exploitation enables attackers to access Livepatch services using the victim's credentials, potentially causing issues to the Livepatch server and compromising the integrity of the system's patch management infrastructure.

Affected Products

• Canonical Livepatch Snap Client versions prior to 10.15.0
• Ubuntu systems with Livepatch client enabled
• Systems with active Ubuntu Pro subscriptions

Discovery Timeline

• April 20, 2026 - CVE-2026-6369 published to NVD
• April 20, 2026 - Last updated in NVD database

Technical Details for CVE-2026-6369

Vulnerability Analysis

This vulnerability is classified under CWE-306 (Missing Authentication for Critical Function). The canonical-livepatch snap client fails to properly authenticate requests made to its Unix domain socket (livepatchd.sock). This architectural weakness allows any local user on the system to communicate with the privileged livepatch daemon without providing proper credentials or authorization.

The attack requires local access to the affected system and the Livepatch client must already be enabled with a valid Ubuntu Pro subscription. When these conditions are met, an unprivileged user can craft requests to the socket and retrieve the root-level authentication token that the livepatch daemon uses to communicate with Canonical's Livepatch service.

Root Cause

The root cause of this vulnerability stems from inadequate access control implementation on the livepatchd.sock Unix domain socket. The socket lacks proper authentication mechanisms to verify the identity and privilege level of connecting clients before processing their requests. This design oversight allows unprivileged local users to access sensitive functionality that should be restricted to root or authorized processes only.

Attack Vector

The attack is executed locally (AV:L) with low complexity. An attacker must have local access to the vulnerable system with a low-privilege user account. The attack flow involves:

1. Identifying a system running the vulnerable canonical-livepatch snap client
2. Locating the livepatchd.sock Unix domain socket
3. Sending an unauthenticated request to the socket
4. Receiving the root-level authentication token in response
5. Using the stolen token to access Livepatch services or potentially disrupt the Livepatch server

The vulnerability allows for high confidentiality impact as sensitive authentication credentials can be extracted. The stolen token could be used to impersonate the victim system when interacting with Canonical's Livepatch infrastructure.

Detection Methods for CVE-2026-6369

Indicators of Compromise

• Unexpected connections to the livepatchd.sock Unix domain socket from non-root processes
• Unusual access patterns to Livepatch services from the affected system
• Multiple authentication attempts or API calls to Canonical Livepatch servers
• Presence of the authentication token in unexpected locations or processes

Detection Strategies

• Monitor Unix socket connections using tools like ss or lsof to identify unauthorized access attempts to livepatchd.sock
• Implement file integrity monitoring on the livepatch snap directory and configuration files
• Review system logs for unusual livepatch-related activity from unprivileged user accounts
• Deploy endpoint detection solutions to alert on suspicious socket communication patterns

Monitoring Recommendations

• Enable audit logging for socket access using auditd with rules targeting the livepatchd socket path
• Configure SIEM alerts for anomalous local privilege escalation patterns
• Monitor outbound connections to Canonical Livepatch API endpoints for unusual request volumes or timing
• Regularly review user activity on systems with Livepatch enabled

How to Mitigate CVE-2026-6369

Immediate Actions Required

• Update the canonical-livepatch snap client to version 10.15.0 or later immediately
• Audit systems to identify which have the vulnerable Livepatch client installed
• Review access logs for any signs of prior exploitation
• Consider regenerating Livepatch authentication tokens on potentially compromised systems

Patch Information

Canonical has addressed this vulnerability in canonical-livepatch snap client version 10.15.0. Organizations should update to this version or later to remediate the improper access control issue. Refer to the Ubuntu Security Notice for official guidance on the patch.

To update the snap package, administrators can use the standard snap refresh mechanism. The update implements proper authentication checks on the Unix domain socket to prevent unauthorized access to the root-level authentication token.

Workarounds

• Restrict physical and SSH access to affected systems to trusted users only
• Implement additional access controls on the socket file using system hardening measures if patch deployment is delayed
• Consider temporarily disabling the Livepatch client on high-risk systems until the update can be applied
• Monitor affected systems closely for suspicious local user activity

# Update canonical-livepatch snap to patched version
sudo snap refresh canonical-livepatch

# Verify installed version is 10.15.0 or later
snap info canonical-livepatch | grep installed

# Review current socket permissions (informational)
ls -la /run/snapd/ns/ | grep livepatch