EUVD-2026-44910
GHSA-4m5m-x42p-vrwg
Severity by source
AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Local-only /proc read attack requires existing low-privilege account (PR:L, AV:L); full token disclosure warrants C:H with no integrity or availability impact.
Primary rating from Vendor (canonical).
CVSS VectorVendor: canonical
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N
Lifecycle Timeline
2DescriptionCVE.org
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.
AnalysisAI
ubuntu-pro-client (formerly ubuntu-advantage-tools) leaks Ubuntu Pro bearer tokens to unprivileged local users via the Linux /proc filesystem on all supported Ubuntu LTS releases from 14.04 through 26.04. When the client validates APT credentials, it spawns /usr/lib/apt/apt-helper with the secret token embedded in a cleartext URL argument (https://bearer:<token>@esm.ubuntu.com/), which any local low-privileged user can read from /proc/<pid>/cmdline on default-configured systems. …
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Attack ChainAIDerived
Hypothetical attack flow derived from CVE metadata
Vulnerability AssessmentAI
| Exploitation | Exploitation requires three concurrent conditions: (1) the attacker possesses a local low-privileged account on the target system (confirmed by PR:L in the CVSS vector); (2) the target system's /proc filesystem is mounted without hidepid restrictions - this is the Ubuntu default across all affected LTS versions and requires no special configuration to be present; and (3) ubuntu-pro-client must be actively executing credential validation (e.g., during 'apt update', 'pro attach', or ESM repository access), causing apt-helper to be spawned with the token-bearing URL in argv. … Additional conditions and limiting factors are described in the full assessment. |
| Risk Assessment | The NVD CVSS 5.5 vector (AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:N/A:N) is well-calibrated to the actual threat: exploitation is local-only and requires an existing low-privileged account, but once those conditions are met, token extraction is straightforward with no special tooling. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in. |
| Exploit Scenario | A low-privileged attacker on a shared Ubuntu server runs a tight polling loop reading all entries under /proc/*/cmdline, waiting for the apt-helper process to appear during a scheduled 'apt update' or 'pro attach' operation. The moment the helper spawns, the attacker captures the full URL argument containing the bearer token in the format https://bearer:<token>@esm.ubuntu.com/ before the short-lived process exits. … |
| Remediation | The primary fix is to upgrade ubuntu-pro-client to the patched package version via 'sudo apt update && sudo apt install ubuntu-advantage-tools'; consult the Canonical advisory at https://ubuntu.com/security/CVE-2026-9494 for the exact fixed version number, which was not confirmed in available data at time of analysis. … Detailed patch versions, workarounds, and compensating controls in full report. |
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External POC / Exploit Code
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