CVE-2026-9494
MediumCVSS 5.5Summary
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 with the secret bearer token embedded directly in the cleartext URL passed via command-line arguments (argv). On systems with a default-mounted /proc filesystem where process-hiding mitigations (hidepid) are disabled, an unprivileged local attacker can monitor system processes and read the sensitive bearer token from /proc/cmdline while the helper process is running.
Risk Assessment
The leaked bearer token can be used to gain unauthorized access to the victim's Ubuntu Pro or Expanded Security Maintenance (ESM) repositories, compromising the confidentiality and integrity of managed packages.
Recommendation
Immediately update the ubuntu-pro-client package to the latest patched version. As a temporary mitigation, enable hidepid on the /proc filesystem (e.g., mount -o remount,hidepid=2 /proc) and restrict process access for unprivileged users.
Other vulnerabilities in ubuntu-pro-client
See all- CVE-2026-12391Medium
A vulnerability in the ubuntu-pro-client (formerly ubuntu-advantage-tools) pro collect-logs command allows an unprivileged local attacker to create a symbolic link to root-readable files (e.g., /etc/shadow). When an administrator runs the tool, it follows the symlink and includes the sensitive file contents in the diagnostic archive, which is then accessible to the attacker.
- CVE-2026-11386Critical
An input validation vulnerability in ubuntu-pro-client (formerly ubuntu-advantage-tools) allows injection of arbitrary APT repository configurations and installation of malicious packages with root privileges. The issue stems from missing validation of contract server data used to generate APT source files and execute apt-get install commands.
Original NVD description (English source)
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.