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Fencer Intel
medium 5.0

CVE-2026-12391 json

ubuntu-pro-client Local Privilege Escalation and Information Disclosure via Symlink Arbitrary File Read in collect-logs

published 3mo ago modified 3mo ago also EUVD-2026-44912

cvss
5.0
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
0.2%
EPSS 0.2% chance of exploitation in 30 days, percentile 10%
public exploits
0
none known

Summary

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.

Patch / fix

  • Canonical ubuntu-pro-client (ubuntu-advantage-tools) 37.3
  • Canonical Ubuntu 26.04 LTS 37.2ubuntu0.1
  • Canonical Ubuntu 24.04 LTS 37.2ubuntu~24.04.1
  • Canonical Ubuntu 22.04 LTS 37.2ubuntu~22.04.1
  • Canonical Ubuntu 20.04 LTS 37.1ubuntu0~20.04.1
  • Canonical Ubuntu 18.04 LTS 37.1ubuntu0~18.04.1
  • Canonical Ubuntu 16.04 LTS 37.1ubuntu0~16.04.1
  • ubuntu-advantage-tools Ubuntu 22.04 LTS 37.2ubuntu~22.04.1
  • ubuntu-advantage-tools Ubuntu 24.04 LTS 37.2ubuntu~24.04.1
  • ubuntu-advantage-tools Ubuntu 26.04 LTS 37.2ubuntu0.1

ubuntu advisories UBUNTU-CVE-2026-12391

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

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CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
3mo ago

Exploit prediction

0.21% chance of exploitation in the next 30 days, higher than 10% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CNA 3.1 5.0 CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:N/A:N

Affected products

  • Canonical ubuntu-pro-client (ubuntu-advantage-tools)
  • Canonical Ubuntu 26.04 LTS
  • Canonical Ubuntu 24.04 LTS
  • Canonical Ubuntu 22.04 LTS
  • Canonical Ubuntu 20.04 LTS
  • Canonical Ubuntu 18.04 LTS
  • Canonical Ubuntu 16.04 LTS

Classification

Weakness
  • CWE-59 Improper Link Resolution Before File Access

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.