Description

Incorrect privilege assignment vulnerability in Apache Syncope. When the configured JWKS settings for internal JWT authentication are disclosed (at least protocol and key), an attacker can obtain admin privileges after completing a successful authentication and obtaining a valid low-privileges JWT. This issue affects Apache Syncope: from 3.0.0-M0 through 3.0.16, from 4.0.0-M0 through 4.0.7, from 4.1.0-M0 through 4.1.2. Users are recommended to upgrade to version 4.0.8 / 4.1.3, which fix this issue.

Executive Summary

Technical Details

Mitigations

References

Additional Metadata

{
  "score": "9.8",
  "pubDate": "2026-09-14T13:18:47.123Z",
  "pubdate": "2026-09-14T13:18:47.123Z",
  "executiveSummary": "An incorrect privilege assignment vulnerability exists within Apache Syncope, potentially allowing low-privileged authenticated users to escalate privileges to administrative levels.\nThe flaw stems from the insufficient validation or processing of internal JSON Web Tokens (JWT) when the corresponding JSON Web Key Set (JWKS) configuration, specifically the protocol and key material, is disclosed.\nAffected products include Apache Syncope versions 3.0.0-M0 through 3.0.16, 4.0.0-M0 through 4.0.7, and 4.1.0-M0 through 4.1.2.\nSuccessful exploitation requires the attacker to first obtain a valid low-privilege JWT and gain knowledge of the internal JWKS configuration.\nThe risk implication is critical, as unauthorized administrative access allows for full compromise of the identity management system, including user account manipulation, credential exfiltration, and unauthorized service configuration changes.\nExploitation is feasible for any authenticated actor within the environment who can leverage disclosed configuration parameters to forge or manipulate JWT assertions to bypass intended authorization constraints.",
  "technicalDetails": "The vulnerability resides in the JWT authentication mechanism used by Apache Syncope for internal service communication and session management. The core issue involves the improper handling of JWT signature verification or claims validation when the underlying JWKS (JSON Web Key Set) is compromised or leaked.\nIn a secure implementation, the integrity of the JWT is maintained by verifying the signature against a trusted public key retrieved from a protected JWKS endpoint. The vulnerability occurs when the system architecture facilitates a scenario where an attacker can identify the specific key and protocol used for internal token signing.\nThe attack flow proceeds as follows: First, the attacker must acquire a valid, low-privilege JWT through standard authentication processes. Second, the attacker obtains the internal JWKS configuration details, specifically the protocol and the public/private key material associated with the token issuance. Third, leveraging the disclosed key information, the attacker constructs or modifies a JWT payload. By manipulating the claims within the token—specifically those defining the user's role and privilege set—the attacker can escalate their status within the Syncope framework.\nBecause the validation logic relies on the compromised JWKS settings, the application improperly trusts the forged token. The signature verification process fails to detect the unauthorized modification because the attacker utilizes the disclosed key material to re-sign the token. Once submitted to the server, the application processes the forged token, grants the requested administrative privileges, and permits access to privileged administrative functions.\nThis vulnerability effectively bypasses the Role-Based Access Control (RBAC) mechanisms implemented by Apache Syncope. The exploitation path does not necessarily require a sophisticated cryptographic break; rather, it exploits the exposure of secret or internal configuration parameters that should be restricted to the server environment. Once administrative access is achieved, the attacker can perform unauthorized modifications to the identity store, manipulate security policies, or conduct further lateral movement within the network protected by the Syncope instance.\nThe issue affects versions 3.0.0-M0 through 3.0.16, 4.0.0-M0 through 4.0.7, and 4.1.0-M0 through 4.1.2. The security of the JWT issuance and verification chain is fundamentally undermined by the disclosure of the JWKS configuration, necessitating an immediate transition to patched versions 4.0.8 or 4.1.3 to enforce robust key management and token integrity."
}