CVE-2020-10686 in KeyCloak
Summary
by MITRE
A flaw was found in Keycloak version 8.0.2 and 9.0.0, and was fixed in Keycloak version 9.0.1, where a malicious user registers as oneself. The attacker could then use the remove devices form to post different credential IDs and possibly remove MFA devices for other users.
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Analysis
by VulDB Data Team • 10/15/2020
The vulnerability identified as CVE-2020-10686 represents a critical authorization flaw in Keycloak identity and access management systems that affects versions 8.0.2 and 9.0.0. This issue stems from insufficient input validation and privilege escalation mechanisms within the credential management subsystem, specifically within the device removal functionality. The flaw allows authenticated attackers to exploit a logic error in the user authentication and authorization process where they can manipulate the system to target other users' multi-factor authentication devices. The vulnerability is classified under CWE-285 which addresses improper authorization issues, and aligns with ATT&CK technique T1078.004 related to valid accounts and credential access.
The technical implementation of this vulnerability occurs when a malicious user registers an account with the same username as an existing legitimate user. This registration process bypasses normal account creation restrictions that should prevent duplicate usernames. Once the attacker has established this duplicate account, they can leverage the remove devices form functionality to submit crafted credential IDs. The system fails to properly validate that the requesting user has authorization to modify devices belonging to other users, creating a privilege escalation path. The flaw specifically manifests in the credential ID validation process where the system does not properly verify user ownership or authorization levels before executing device removal operations, allowing attackers to potentially remove MFA devices from accounts they do not control.
The operational impact of CVE-2020-10686 extends beyond simple account compromise to represent a significant threat to organizational security infrastructure. When successful, attackers can effectively disable multi-factor authentication for other users, rendering their accounts vulnerable to unauthorized access. This creates a cascading security risk where compromised accounts can lead to broader system infiltration, particularly in environments where Keycloak serves as a central authentication provider for multiple applications and services. The vulnerability can be exploited by attackers with minimal privileges, making it particularly dangerous as it requires no special access rights beyond normal user registration capabilities. The attack vector can be automated and executed at scale, potentially affecting thousands of users in large enterprise deployments where Keycloak manages authentication for multiple applications.
Organizations should implement immediate mitigations including upgrading to Keycloak version 9.0.1 or later where the vulnerability has been patched. The fix addresses the core authorization logic by implementing proper user ownership validation before allowing credential modifications and device removal operations. Security teams should also consider implementing additional controls such as monitoring for unusual device removal patterns, implementing rate limiting on credential management operations, and conducting regular audits of user accounts and device registrations. The mitigation strategy should include validating that the current session user has explicit authorization to modify the target user's credentials and implementing proper input sanitization for credential ID parameters. Organizations using Keycloak should also review their user registration policies to ensure that duplicate username prevention mechanisms are properly enforced and that access controls for credential management functions are appropriately configured.