Review reviewCritical

CVE-2026-11386

Canonical ubuntu-pro-client (ubuntu-advantage-tools), Ubuntu 26.04 LTS, Ubuntu 24.04 LTS

An input validation and injection vulnerability exists in Canonical ubuntu-pro-client (formerly ubuntu-advantage-tools). The client constructs APT source files (such as /etc/apt/sources.list.d/ubuntu-.list or their DEB822 equivalents) using data received directly from the contract server response via the directives.suites[] and directives.aptURL fields. Because the client utilizes Python's str.format() to write these files without performing escaping, validation, or newline character filtering, a malicious or tampered contract response containing embedded newline (\n) characters can success...

CVSS: 9
EPSS: 0.34%
CISA KEV: Not listed
Published: 2026.07.16

PRIORITY ASSESSMENT

Review review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV

Exploit probability0.34%

Technical severityCVSS 9

Vulnerability overview

Affected product and versions

Product: Canonical ubuntu-pro-client (ubuntu-advantage-tools), Ubuntu 26.04 LTS, Ubuntu 24.04 LTS
Affected versions: < 37.3
Fixed versions: No verified fixed-version field is available yet

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide

1
Identify
Confirm that Canonical ubuntu-pro-client (ubuntu-advantage-tools), Ubuntu 26.04 LTS, Ubuntu 24.04 LTS and an affected version are present.
2
Prioritize
Combine exploitation signals with asset exposure and business criticality.
3
Remediate
Follow the vendor advisory or supported update path and preserve rollback options.
4
Verify
Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
CWE: CWE-20