Keycloak — CraftedSignal Threat Feedhttps://feed.craftedsignal.io/vendors/keycloak/Trending threats, MITRE ATT&CK coverage, and detection metadata. Fed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioWed, 13 May 2026 07:59:27 +0000Keycloak Vulnerability Allows Arbitrary Email Sendinghttps://feed.craftedsignal.io/briefs/2026-05-keycloak-email-vuln/Wed, 13 May 2026 07:59:27 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-05-keycloak-email-vuln/An anonymous, remote attacker can exploit a vulnerability in Keycloak to send arbitrary emails, potentially leading to phishing or social engineering attacks.A vulnerability exists within Keycloak that allows an unauthenticated, remote attacker to send arbitrary emails. The BSI advisory (WID-SEC-2025-1870) highlights the potential for exploitation. This vulnerability is significant because it enables attackers to leverage Keycloak’s email functionality for malicious purposes, such as sending phishing emails, distributing malware, or conducting social engineering attacks against users of systems integrated with Keycloak. Successful exploitation could damage trust in the platform and compromise user accounts.

Attack Chain

  1. Attacker identifies a Keycloak instance exposed to the internet.
  2. Attacker crafts a malicious request exploiting the email sending vulnerability.
  3. The malicious request bypasses authentication and authorization checks related to email functionality.
  4. Keycloak processes the attacker’s request without proper validation.
  5. Keycloak’s email service sends an email with attacker-controlled content.
  6. The email is delivered to the targeted recipient(s).
  7. The recipient interacts with the malicious email (e.g., clicks a link, opens an attachment).
  8. The attacker achieves their objective (e.g., credential harvesting, malware infection).

Impact

Successful exploitation of this vulnerability could lead to the distribution of phishing emails, malware, or other malicious content, potentially compromising user accounts or systems integrated with Keycloak. The impact includes potential reputational damage, data breaches, and financial losses. While the number of affected systems is not specified in the advisory, all Keycloak instances are potentially vulnerable if not patched.

Recommendation

  • Upgrade Keycloak to the latest patched version to remediate the email sending vulnerability.
  • Monitor Keycloak logs for suspicious email activity, as detected by the Sigma rule “Detect Suspicious Keycloak Email Activity”.
  • Implement rate limiting on email sending functionality within Keycloak to mitigate abuse, and monitor for bypass attempts.
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