CVE-2026-15943 in Keycloak
Summary
by MITRE • 07/17/2026
A flaw was found in the Keycloak keycloak-services component, which handles the management of identity providers. The issue occurs when a delegated administrator updates an OIDC identity provider using a masked client secret sentinel value. Due to improper validation, Keycloak reuses the existing real secret even if security-sensitive fields like the token URL have been changed, allowing an attacker to redirect and capture the secret.
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Analysis
by VulDB Data Team • 07/17/2026
This vulnerability resides within the keycloak-services component of the Keycloak identity management platform, specifically affecting how delegated administrators manage identity providers through the OpenID Connect protocol. The flaw manifests when administrators attempt to update OIDC identity provider configurations using a masked client secret sentinel value, which represents a critical weakness in the authentication and authorization validation mechanisms. The vulnerability is categorized under CWE-284 Access Control Issues, as it allows unauthorized privilege escalation through improper validation of security-sensitive fields during administrative operations.
The technical implementation flaw occurs at the validation layer where Keycloak fails to properly verify that all security-relevant parameters have been genuinely modified before accepting updates to identity provider configurations. When a delegated administrator attempts to update an OIDC identity provider and provides a masked sentinel value for the client secret, the system incorrectly assumes that no actual change has occurred to the sensitive credential, thereby preserving the original real secret value even when other critical fields such as token URL have been modified. This behavior creates an exploitable condition where attackers can manipulate the authentication flow without actually knowing or possessing the legitimate client secret.
The operational impact of this vulnerability extends beyond simple credential exposure, creating a potential attack vector for man-in-the-middle operations and credential harvesting. An attacker who gains access to a delegated administrator account could exploit this flaw by modifying the token URL field to point to a malicious endpoint while maintaining the original valid secret, effectively allowing them to intercept authentication tokens and potentially gain unauthorized access to protected resources. This vulnerability directly maps to ATT&CK technique T1566 Phishing for Information within the credential access phase, as it enables attackers to capture secrets through manipulated authentication flows rather than traditional brute force or social engineering methods.
The security implications are particularly severe given that delegated administrators typically possess elevated privileges within specific realms or applications, making this vulnerability a potential pathway for lateral movement and privilege escalation throughout the identity management infrastructure. Organizations using Keycloak deployments with delegated administrative capabilities face significant risk from this flaw, as it undermines the fundamental security assumptions of credential management and validation processes. The vulnerability demonstrates a critical gap in the principle of least privilege implementation, where proper validation of all fields during update operations is not enforced, allowing attackers to maintain access through legitimate administrative channels while manipulating authentication parameters.
Mitigation strategies should focus on implementing comprehensive input validation for all security-sensitive fields during administrative updates, ensuring that when any parameter changes occur within OIDC identity provider configurations, the system performs complete validation rather than relying on sentinel values or partial field comparisons. Organizations should also consider implementing additional monitoring and alerting mechanisms to detect unusual patterns in identity provider configuration changes, particularly those involving token URL modifications without corresponding secret updates. The fix should enforce strict validation that requires explicit re-authentication or credential re-entry when critical security parameters such as token URLs are modified, preventing the automatic reuse of existing secrets during administrative updates.