CVE-2026-12391

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.

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.

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.

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.

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.

• Bump epoch to supersede the vendor package in the ELS channel (matches the ubuntu16/ubuntu18 ELS branches).
• Add gpg to Build-Depends: the build-time test suite (uaclient/tests/test_gpg.py) invokes the gpg binary, which is not present in the minimal ELS build chroot.
• Add debian/mark_skip_pytests.sh and invoke it from debian/rules: on FIPS-capable build hosts running in a disabled state, some status/FIPS pytests fail at build time; skip only those, only in that environment (matches the ubuntu16/ubuntu18 ELS branches).
• Skip tools/check-versions-are-consistent.py in override_dh_auto_build: its regex does not handle a package epoch and misparses our 1:34~20.04+tuxcare.elsN version, aborting the build; version.py already matches the shipped upstream version (34).
• SECURITY UPDATE: Pro bearer token exposed via apt-helper command line
  • Write APT credentials to a temporary 0600 auth file and pass a credential-free URL to apt-helper, instead of embedding the token in the download-file URL argument where it leaked to local users via /proc/<pid>/cmdline. Source tarball re-packed with the fix (3.0 native).
  • cve-2026-9494
• SECURITY UPDATE: APT source injection via crafted contract-server response
  • validate contract directives (aptURL, suites, additionalPackages) to reject newline/CR/NUL/space characters, preventing injection of attacker-controlled lines into root-owned apt sources and the apt-get install invocation. Source tarball re-packed with the fix (3.0 native).
  • cve-2026-11386
• SECURITY UPDATE: symlink file disclosure in "pro collect-logs"
  • Skip symlinked user log files and create the diagnostic archive exclusively (x:gz) with a root-only umask so an existing output file or symlink is not followed or overwritten. Source tarball re-packed with the fix (3.0 native).
  • cve-2026-12391

• SECURITY UPDATE: Pro bearer token exposed via apt-helper command line
  • Write APT credentials to a temporary 0600 auth file and pass a credential-free URL to apt-helper, instead of embedding the token in the download-file URL argument where it leaked to local users via /proc/<pid>/cmdline. Source tarball re-packed with the fix (3.0 native).
  • cve-2026-9494
• SECURITY UPDATE: APT source injection via crafted contract-server response
  • validate contract directives (aptURL, suites, additionalPackages) to reject newline/CR/NUL/space characters, preventing injection of attacker-controlled lines into root-owned apt sources and the apt-get install invocation. Source tarball re-packed with the fix (3.0 native).
  • cve-2026-11386
• SECURITY UPDATE: symlink file disclosure in "pro collect-logs"
  • Skip symlinked user log files and create the diagnostic archive exclusively (x:gz) with a root-only umask so an existing output file or symlink is not followed or overwritten. Source tarball re-packed with the fix (3.0 native).
  • cve-2026-12391

Bilal Teke discovered that Ubuntu Advantage Tools exposed the Pro bearer token in command-line arguments when validating APT credentials. A local attacker could possibly use this issue to obtain sensitive information and gain unauthorized access to Ubuntu Pro repositories. (CVE-2026-9494)

Frederick Jerusha discovered that Ubuntu Advantage Tools did not properly validate data received from the contract server when writing APT source files. An attacker could possibly use this issue to inject arbitrary APT configuration and execute arbitrary code. (CVE-2026-11386)

Mateusz Gierblinski discovered that Ubuntu Advantage Tools did not properly handle symbolic links when collecting diagnostic logs. A local attacker could possibly use this issue to obtain sensitive information from files owned by the administrator. This issue only affected Ubuntu 16.04 LTS, Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, Ubuntu 22.04 LTS, Ubuntu 24.04 LTS and Ubuntu 26.04 LTS. (CVE-2026-12391)