CVE-2026-3012
Description
A flaw was found in Samba’s certificate auto-enrollment Group Policy handling. When certificate auto-enrollment is enabled, Samba may retrieve a CA certificate over an unencrypted HTTP connection and install it into the local trust store without proper verification. An attacker with the ability to intercept or redirect network traffic could exploit this behavior to supply a malicious certificate authority certificate, potentially allowing interception or spoofing of trusted communications.
Statement
Red Hat Product Security has rated this vulnerability as Important severity.
However, exploitation requires several specific non-default conditions to be met. The vulnerable code path is only reachable when Samba Group Policy processing is explicitly enabled using the apply group policies = yes configuration option and certificate auto-enrollment is configured through Group Policy.
Hence, although the vulnerable code is present, it is not exploitable in default RHEL configurations.
In addition, the attacker must have the ability to intercept or redirect adjacent-network HTTP traffic during certificate retrieval. Because exploitation depends on explicit administrative configuration changes and adjacent-network positioning, Red Hat assesses the attack complexity as High (AC:H).
Mitigation
Systems are not affected unless Samba Group Policy processing and certificate auto-enrollment are explicitly enabled.
Administrators can reduce exposure by:
Avoiding unnecessary use of certificate auto-enrollment.
Ensuring your "smb.conf" does not contain a line like
apply group policies = yes. If , group policy is not be enabled, the vulnerable code will not run.
Intercepting the HTTP request requires some control over the local network or other devices to intercept or redirect traffic. Some network administrators might assess this as a low risk on their
networks.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 8 | 6.8 | 8 |
| Attack Vector | Adjacent Network | Adjacent Network | Adjacent Network |
| Attack Complexity | High | High | High |
| Privileges Required | None | None | None |
| User Interaction | None | None | None |
| Scope | Changed | Unchanged | Changed |
| Confidentiality | High | High | High |
| Integrity Impact | High | High | High |
| Availability Impact | None | None | None |
Vector
Red Hat: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
NVD: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
cve.org: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:N
Understanding the Weakness (CWE)
Integrity,Other
Technical Impact: Varies by Context; Unexpected State
Acknowledgements
Red Hat would like to thank Arad Inbar (DREAM Security Research Team), Ben Grinberg (DREAM Security Research Team), Michalis Vasileiadis, and Nir Somech (DREAM Security Research Team) for reporting this issue.
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