CVE-2026-107121 MEDIUM

CVE-2026-107121: Keycloak-services: keycloak-services: smtp starttls plaintext credential and message downgrade

Vendor Red Hat
Product Red Hat Build of Keycloak
Weakness CWE-319 · Cleartext transmission
Published October 7, 2026
Last update October 7, 2026

CVSS base score

6.5/10
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Confidentiality High
Integrity Low

CVSS vector

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N

What the vulnerability does

01Description

A flaw was found in the SMTP email configuration handling of the keycloak-services component. When the STARTTLS option is enabled, Keycloak fails to strictly enforce an encrypted connection, allowing it to fall back to unencrypted communication if the encryption request is tampered with. An attacker who can intercept network traffic can exploit this to capture sensitive email credentials and message content in plain text.

Key dates

02Disclosure timeline

October 7, 2026 CVE published