CVE-2026-3012: Samba: group policy certificate enrollment uses http:// without validation

Severity: medium (CVSS 6.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-05-27 · updated 2026-10-26
Weakness: CWE-345

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.

Affected products

Red Hat Enterprise Linux: 7.0, 9.0
Red Hat OpenShift Container Platform 4.18: 4.0
Samba: from 4.16.0 before 4.21.0 — fixed in 4.21.0

How to fix

Upgrade to a fixed version: Samba 4.21.0. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-3012 or the next vulnerability affects your stack