CVE-2026-12391 ubuntu-pro-client Local Privilege Escalation and Information Disclosure via Symlink Arbitrary File Read in collect-logs
Local attackers can read root-owned files via symlink attacks in the pro collect-logs command, leading to information disclosure and potential privilege escalation.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Local or same network only
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-12391?
CVE-2026-12391 is a medium-severity path traversal vulnerability in Canonical Ubuntu 16.04 LTS, published on 16 Jul 2026. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Official description
An insecure symlink following vulnerability exists in Canonical ubuntu-pro-client (formerly ubuntu-advantage-tools) within the pro collect-logs command framework. The utility creates or utilizes predictable temporary file paths or user-accessible log directories when gathering diagnostic information without verifying the file type or ownership. An unprivileged local attacker can exploit this behavior by creating a symbolic link (symlink) at a predictable destination path pointing to an arbitrary, root-readable file (such as /etc/shadow or private files within /root). When a root administrator or operator subsequently executes the pro collect-logs command, the tool follows the user-controlled symlink, reads the target file, and compresses its contents into the resulting diagnostic support archive. Because the output archive remains readable by the unprivileged user, the attacker can extract and read the sensitive root-owned files, leading to a complete information disclosure of system secrets.
Weakness: CWE-59
Which versions are affected by CVE-2026-12391?
How do I fix CVE-2026-12391?
Apply the vendor's patch.
Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.
Is CVE-2026-12391 being exploited?
There is no known exploitation of CVE-2026-12391 in the wild and no public exploit code.
Sources
Also known as GHSA-whf7-7mxf-ww93, UBUNTU-CVE-2026-12391.