Man-in-the-Middle Vulnerability in Canonical ADSys Affecting Secure Certificate Handling
CVE-2026-12249

9CRITICAL

Key Information:

Status
Ubuntu 20.04 Lts
Ubuntu 22.04 Lts
Ubuntu 24.04 Lts
Vendor
CVE Published:
22 June 2026

What is CVE-2026-12249?

A vulnerability was found in Canonical ADSys that may allow unauthorized access to secure systems. This is due to the use of an insecure HTTP connection during the Active Directory Certificate Services (AD CS) certificate auto-enrollment process. The vendored Samba client script sends requests in plaintext, making it susceptible to Man-in-the-Middle (MITM) attacks. An attacker could intercept the connection and inject a malicious Root CA certificate, leading to trust store poisoning. As a result, the system may accept rogue certificates for any domain, facilitating persistent decryption and interception of TLS communications. This vulnerability is addressed in version v0.16.3.

References

https://ubuntu.com/security/CVE-2026-12249
vdb-entryissue-tracking
https://github.com/ubuntu/adsys/commit/8b1939f96d3827b442...
patch

CVSS V4

Score:
9
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
High
Attack Required:
None
Privileges Required:
Undefined
User Interaction:
None

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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