CVE-2026-11386 — Canonical ubuntu-pro-client (ubuntu-advantage-tools)
As of 2026-07-16, CVE-2026-11386 is a CRITICAL-severity vulnerability in Canonical ubuntu-pro-client (ubuntu-advantage-tools), CVSS v3.1 9, EPSS 0.3% (23.8th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-11386, most recently “Critical Ubuntu Pro Client Vulnerability Enables Root Code Execution via Contract Server Spoofing (CVE-2026-11386)”.
Last updated: 2026-07-16
What is CVE-2026-11386?
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 successfully inject arbitrary, attacker-controlled deb configuration lines into root-owned APT sources. When combined with the unvalidated additionalPackages[] field—which is passed positionally into a root-executed apt-get install command—an attacker capable of spoofing or manipulating the contract response (e.g., via a compromised internal infrastructure, an intercepted connection utilizing a trusted CA, or local logical bugs) can force the client to fetch and install malicious packages. This ultimately leads to arbitrary code execution with root privileges on the affected system. This component is preinstalled on supported Ubuntu Server releases and auto-attaches by default on cloud provider Ubuntu Pro images.
The record classifies CVE-2026-11386 under weakness class CWE-20. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 8 affected-product entries are recorded, across 1 vendor, listed below. The identifier was first published 59 days ago.
Severity and exploitation probability
- CVSS v3.1 base score
- 9 — CRITICAL
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H - EPSS (FIRST)
- 0.3% probability of exploitation in the next 30 days, higher than 23.8% of all scored CVEs
- CISA KEV
- Not listed in the CISA Known Exploited Vulnerabilities catalog
- Threadlinqs priority
- 5.5/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- Published
- 2026-07-16
Is CVE-2026-11386 being exploited?
No public exploitation evidence for CVE-2026-11386 is recorded in the sources Threadlinqs tracks — CISA KEV, Exploit-DB, public proof-of-concept repositories and ProjectDiscovery Nuclei — as of 2026-07-16. That is an absence of evidence in those feeds, not a guarantee that the vulnerability is unexploited.
Affected products and versions
- Canonical: ubuntu-pro-client (ubuntu-advantage-tools), Ubuntu 26.04 LTS, Ubuntu 24.04 LTS, Ubuntu 22.04 LTS, Ubuntu 20.04 LTS, Ubuntu 18.04 LTS, Ubuntu 16.04 LTS, Ubuntu 14.04 LTS
How to fix CVE-2026-11386
No vendor patch reference has been recorded for CVE-2026-11386 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.
Threat activity tracking CVE-2026-11386
1 tracked threat in the Threadlinqs corpus references CVE-2026-11386, either in the campaign’s CVE list or as an indicator on the campaign record.
- Critical Ubuntu Pro Client Vulnerability Enables Root Code Execution via Contract Server Spoofing (CVE-2026-11386) — CRITICAL · 2026-07-20
Sources
Enriched from CVE.org, NVD, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on . This product uses the NVD API but is not endorsed or certified by the NVD.
Vulnerability database entry
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