CVE-2026-12249
Canonical ADSys Trust Store Poisoning via Plaintext HTTP Certificate Auto-Enrollment
Description
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.
INFO
Published Date :
June 22, 2026, 6:16 p.m.
Last Modified :
June 22, 2026, 8:18 p.m.
Remotely Exploit :
Yes !
Source :
[email protected]
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS | 134c704f-9b21-4f2e-91b3-4a467353bcc0 | |||||
| CVSS 3.1 | HIGH | cc1ad9ee-3454-478d-9317-d3e869d708bc | ||||
| CVSS 3.1 | CRITICAL | MITRE-CVE | ||||
| CVSS 3.1 | CRITICAL | [email protected] | ||||
| CVSS 4.0 | CRITICAL | cc1ad9ee-3454-478d-9317-d3e869d708bc | ||||
| CVSS 4.0 | CRITICAL | [email protected] |
Solution
- Update ADSys to version v0.16.3.
- Ensure AD CS communication uses HTTPS.
- Verify system trust store integrity.
- Review network traffic for MITM attempts.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-12249.
| URL | Resource |
|---|---|
| https://github.com/ubuntu/adsys/commit/8b1939f96d3827b4426eb06c1ced5bf317b0a99d | |
| https://ubuntu.com/security/CVE-2026-12249 |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-12249 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-12249
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-12249 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-12249 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
Jun. 22, 2026
Action Type Old Value New Value Added SSVC {'id': 'CVE-2026-12249', 'role': 'CISA Coordinator', 'options': [{'exploitation': 'none'}, {'automatable': 'no'}, {'technicalImpact': 'total'}], 'version': '2.0.3', 'timestamp': '2026-06-22T17:30:38.451893Z'} -
New CVE Received by [email protected]
Jun. 22, 2026
Action Type Old Value New Value Added Affected [{'repo': 'https://github.com/ubuntu/adsys', 'versions': [{'status': 'affected', 'version': '0.13.0', 'lessThan': '0.16.3', 'versionType': 'semver'}], 'packageName': 'adsys', 'collectionURL': 'https://github.com/ubuntu', 'defaultStatus': 'unaffected'}, {'repo': 'https://launchpad.net/ubuntu/+source/adsys', 'vendor': 'Canonical', 'product': 'Ubuntu 20.04 LTS', 'versions': [{'status': 'unaffected', 'version': '0.9.2~20.04.2ubuntu0.1+esm2', 'versionType': 'dpkg'}], 'platforms': ['Linux'], 'packageName': 'adsys', 'collectionURL': 'https://launchpad.net/ubuntu/focal', 'defaultStatus': 'unaffected'}, {'repo': 'https://launchpad.net/ubuntu/+source/adsys', 'vendor': 'Canonical', 'product': 'Ubuntu 22.04 LTS', 'versions': [{'status': 'unaffected', 'version': '0.16.3~22.04.2ubuntu0.22.04.1', 'versionType': 'dpkg'}], 'platforms': ['Linux'], 'packageName': 'adsys', 'collectionURL': 'https://launchpad.net/ubuntu/jammy', 'defaultStatus': 'affected'}, {'repo': 'https://launchpad.net/ubuntu/+source/adsys', 'vendor': 'Canonical', 'product': 'Ubuntu 24.04 LTS', 'versions': [{'status': 'unaffected', 'version': '0.16.3~24.04.2ubuntu0.24.04.1', 'versionType': 'dpkg'}], 'platforms': ['Linux'], 'packageName': 'adsys', 'collectionURL': 'https://launchpad.net/ubuntu/noble', 'defaultStatus': 'affected'}, {'repo': 'https://launchpad.net/ubuntu/+source/adsys', 'vendor': 'Canonical', 'product': 'Ubuntu 25.10', 'versions': [{'status': 'unaffected', 'version': '0.16.3', 'versionType': 'dpkg'}], 'platforms': ['Linux'], 'packageName': 'adsys', 'collectionURL': 'https://launchpad.net/ubuntu/questing', 'defaultStatus': 'unaffected'}, {'repo': 'https://launchpad.net/ubuntu/+source/adsys', 'vendor': 'Canonical', 'product': 'Ubuntu 26.04 LTS', 'versions': [{'status': 'unaffected', 'version': '0.16.4ubuntu1', 'versionType': 'dpkg'}], 'platforms': ['Linux'], 'packageName': 'adsys', 'collectionURL': 'https://launchpad.net/ubuntu/resolute', 'defaultStatus': 'unaffected'}] Added Description 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. Added CVSS V4.0 AV:N/AC:H/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H/E:P/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:N/AU:Y/R:I/V:D/RE:L/U:Red Added CVSS V3.1 AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H Added CWE CWE-348 Added Reference https://github.com/ubuntu/adsys/commit/8b1939f96d3827b4426eb06c1ced5bf317b0a99d Added Reference https://ubuntu.com/security/CVE-2026-12249