CVE-2026-9494
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Information Disclosure in Ubuntu Pro Client via /proc/cmdline Exposure

Publication date: 2026-07-16

Last updated on: 2026-07-16

Assigner: Canonical Ltd.

Description
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.

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Meta Information

Published
2026-07-16
Last Modified
2026-07-16
Generated
2026-07-16
AI Q&A
2026-07-16
EPSS Evaluated
N/A
NVD
CVE-2026-9494
EUVD
EUVD-2026-44910

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
canonical ubuntu_pro_client *

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-214 A process is invoked with sensitive command-line arguments, environment variables, or other elements that can be seen by other processes on the operating system.

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Executive Summary

This is an information disclosure vulnerability in Canonical's ubuntu-pro-client where a secret bearer token is exposed in a URL passed via command-line arguments. The token is visible in /proc/cmdline on systems without process-hiding mitigations, allowing local attackers to read it and gain unauthorized access to Ubuntu Pro or ESM repositories.

Detection Guidance

Monitor /proc/cmdline for processes containing 'bearer:' tokens in URLs. Check for ubuntu-pro-client helper processes running with sensitive arguments. Use 'ps aux | grep apt-helper' to identify suspicious command lines.

Impact Analysis

An unprivileged local attacker could exploit this to steal your Ubuntu Pro or ESM repository access token. This token could then be used to access restricted repositories, potentially downloading or modifying software without your consent.

Compliance Impact

This vulnerability could potentially affect compliance with GDPR and HIPAA by exposing sensitive bearer tokens through process monitoring. Unauthorized access to Ubuntu Pro or ESM repositories may lead to unauthorized data access or modifications, violating confidentiality requirements in GDPR and HIPAA.

Mitigation Strategies

Apply vendor patches for ubuntu-pro-client. Enable hidepid on /proc to restrict process visibility. Rotate all exposed Ubuntu Pro bearer tokens immediately. Monitor repository access logs for unauthorized usage.

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