CVE-2026-12249
CRITICALDescription
An issue was discovered in Canonical ADSys upstream versions through v0.16.2. During Active Directory Certificate Services (AD CS) certificate auto-enrollment via the vendored Samba client script (internal/policies/certificate/python/vendor_samba/gp/gp_cert_auto_enroll_ext.py), ADSys utilizes a plaintext HTTP connection (http://) instead of a secure HTTPS connection (https://) to request the CA certificate from the Active Directory Certificate Services server (GetCACert). An unauthenticated network attacker positioned between the managed Ubuntu host and the configured AD CS CA hostname can conduct a Man-in-the-Middle (MITM) attack. By intercepting the plaintext HTTP request, the attacker can supply an arbitrary, attacker-controlled Root CA certificate. Because the system automatically accepts this certificate and registers it into the local system trust store via update-ca-certificates, this results in system-wide trust store poisoning. Consequently, TLS clients utilizing the operating system trust store on the affected machine will accept rogue certificates for arbitrary domains, enabling persistent decryption and interception of subsequent TLS connections. This issue is resolved in version v0.16.3.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H
Exploit Intelligence
Low risk: more likely to be exploited than 4% of all known CVEs.
References
Related Vulnerabilities
Other CWE-348 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-59951 | Critical | 9.1 | 4.7% | - | - |
| CVE-2022-31813 | Critical | 9.8 | 3.3% | - | Fix |
| CVE-2024-45410 | Critical | 9.8 | 1.5% | - | Fix |
| CVE-2021-21373 | High | 7.5 | 1.2% | - | Fix |
| CVE-2021-21374 | High | 8.1 | 1.0% | - | Fix |
| CVE-2022-2255 | High | 7.5 | 0.7% | - | Fix |
Common questions
How do I fix CVE-2026-12249?
No published fix for CVE-2026-12249 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-12249 being actively exploited?
Not that we know of. CVE-2026-12249 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.14% is the estimated probability that it will be exploited in the next 30 days. That is higher than 4% of all scored CVEs.
How severe is CVE-2026-12249?
CVE-2026-12249 has a CVSS v3 base score of 9.0, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-06-22.