What’s Vulnerable › Vulnerabilities

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

• Severity: medium (CVSS 6.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-10-07 · updated 2026-10-07
• Weakness: CWE-319

Description

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.

Affected products

• Red Hat build of Keycloak 26.4: all versions

References

• https://access.redhat.com/security/cve/CVE-2026-107121
• https://bugzilla.redhat.com/show_bug.cgi?id=2547296

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