ubuntu-pro-client Information Disclosure via Cleartext Bearer Token Exposure in Process Command Line

Summary

An information disclosure vulnerability exists in Canonical ubuntu-pro-client (formerly ubuntu-advantage-tools). The client validates Ubuntu Pro APT credentials by executing /usr/lib/apt/apt-helper using the download-file command. During this process, the secret bearer token is embedded directly in the cleartext URL component passed via the command-line arguments (argv), resulting in a URL format such as https://bearer:<token>@esm.ubuntu.com/.../. On systems utilizing a default-mounted /proc file system where process-hiding mitigations (such as hidepid) are disabled, an unprivileged local attacker can monitor system processes and read the sensitive bearer token directly from /proc/cmdline while the helper process is actively running. This leaked token can subsequently be used to gain unauthorized access to the victim's Ubuntu Pro or Expanded Security Maintenance (ESM) repositories.

Timeline

1. Jul 16, 2026, 12:12 PM UTCCVE published
2. Jul 16, 2026, 1:36 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: partial

3. Jul 16, 2026, 3:11 PM UTCRecord last updated

Affected versions

• ubuntu-pro-client

  fixed in 37.3

• ubuntu-advantage-tools

  Version range not reported

• ubuntu-advantage-tools

  Version range not reported

• ubuntu-advantage-tools

  Version range not reported

• ubuntu-advantage-tools

  Version range not reported

• ubuntu-advantage-tools

  Version range not reported

• ubuntu-advantage-tools

  Version range not reported

• ubuntu-advantage-tools

  Version range not reported

References 1