---
id: CVE-2026-107121
title: >-
  A flaw was found in the SMTP email configuration handling of the
  keycloak-services component
summary: >-
  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 commun…
severity: medium
cvss: 6.5
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:L/A:N'
cwe:
  - CWE-319
vendor: Red Hat
product: keycloak-services
affected:
  - keycloak-services (all versions)
  - rhbk/keycloak-rhel9 (all versions)
  - keycloak-services
published: '2026-10-07'
updated: '2026-10-07'
sourceUpdated: '2026-10-07T17:16:53.117'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-107121'
references:
  - url: 'https://access.redhat.com/security/cve/CVE-2026-107121'
    label: secalert@redhat.com
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2547296'
    label: secalert@redhat.com
tags:
  - nvd
  - cve.org
ssvc:
  exploitation: none
  automatable: 'no'
  technicalImpact: partial
  timestamp: '2026-10-07T15:56:53.243244Z'
epss: 0.00084
epssPercentile: 0.00245
ingestedAt: '2026-10-07T08:20:03.945Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.