CVE-2026-73178 in Syncope
Summary
by MITRE • 09/14/2026
Exposure of Sensitive Information to an Unauthorized Actor vulnerability in Apache Syncope.
An administrator with adequate entitlements can get access via REST to the list of existing Access Tokens, including their signed JWT body. These values can be then used to perform further REST requests, impersonating users with higher administration entitlements.
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.
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Analysis
by VulDB Data Team • 09/14/2026
The vulnerability identified in Apache Syncope represents a critical failure in access control and sensitive data exposure mechanisms within the identity governance platform. This flaw allows an authenticated administrator with specific entitlements to retrieve a comprehensive list of existing Access Tokens via REST API endpoints. The severity of this issue is amplified by the fact that these tokens include signed JSON Web Token bodies, which contain encoded user session information and claims. In modern web application architectures relying on stateless authentication protocols like OAuth 2.0 or OpenID Connect, access tokens serve as the primary credential for authorizing subsequent requests to protected resources. The exposure of these tokens effectively compromises the integrity of the authentication layer, allowing attackers to bypass standard login procedures and directly assume active user sessions without needing valid credentials such as passwords or multi-factor authentication factors.
From a technical perspective, this vulnerability stems from an improper restriction on resource access within the REST API implementation. While the system correctly restricts certain administrative functions based on roles, it fails to apply adequate authorization checks when retrieving metadata about existing tokens. This oversight permits any user with basic administrator privileges to enumerate active sessions and extract their cryptographic payloads. Since JWT bodies are typically base64-encoded rather than encrypted, they can be easily decoded by an attacker using standard tools or scripts. Once the token is obtained, its signature ensures that it remains valid for further requests until expiration, meaning the attacker does not need to forge a new token but simply replays the stolen one. This mechanism effectively neutralizes the security boundary between lower-privileged administrators and higher-privileged roles, as the access control logic relies on the validity of the presented token rather than verifying the current user's permissions against the target resource independently during every request phase where sensitive data is exposed.
The operational impact of this vulnerability is severe, primarily facilitating privilege escalation attacks within the Apache Syncope environment. An attacker who gains initial access with low-level administrative rights can leverage these stolen tokens to impersonate users holding higher administration entitlements. This capability allows for unauthorized modification of user identities, alteration of role assignments, and potentially full control over identity lifecycle management processes. Furthermore, because Access Tokens are often used across multiple services integrated with Syncope via SAML or OIDC federation, the compromise can extend beyond the immediate application to downstream systems that trust these tokens. This creates a cascading failure scenario where a single point of weakness in token handling leads to widespread unauthorized access across interconnected enterprise identity infrastructure. The ability to impersonate high-privilege users also facilitates lateral movement and persistence within the organization's network, as the attacker can maintain active sessions without triggering typical credential-based alerts associated with brute force or password spraying attacks.
This vulnerability aligns closely with CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, specifically regarding the improper exposure of authentication credentials through API endpoints. It also maps to ATT&CK technique T1556: Modifying Authentication Process, as it involves altering the expected flow of identity verification by reusing valid session tokens outside their intended context. Additionally, aspects of CWE-284: Improper Access Control are evident in the failure to restrict access to sensitive resource lists based on sufficient privilege levels. The exploitation path resembles T1078: Valid Accounts, where legitimate credentials or sessions are abused for unauthorized access. Mitigation strategies must prioritize immediate patching as recommended by the vendor. Organizations running affected versions from 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 should upgrade to version 4.0.8 or 4.1.3 immediately. These releases contain the necessary code changes to enforce stricter access controls on token enumeration endpoints. In addition to upgrading, administrators should implement robust API gateway policies that monitor for unusual patterns of token retrieval and consider implementing short-lived tokens with strict revocation mechanisms to limit the window of opportunity for exploitation if a leak occurs. Regular auditing of administrative actions and enabling detailed logging for all REST API calls involving sensitive data can also aid in early detection of such enumeration attempts.