CVE-2026-77883 in Syncope
Summary
by MITRE • 09/14/2026
Exposure of sensitive information through data queries vulnerability in Apache Syncope.
An administrator with adequate entitlements for Derived Schemas can create a malicious JEXL expression which allows any administrator with sufficient entitlements for User read to access LinkedAccount's (if present) or Manager's (if defined) sensitive information, possibly including hashed credentials.
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 flaw in the access control and data serialization mechanisms governing derived schemas. This security defect allows an authenticated administrator with specific entitlements related to Derived Schemas to craft malicious Java Expression Language (JEXL) expressions. These expressions are designed to exploit the underlying object graph traversal capabilities during the evaluation of dynamic attributes. By leveraging this capability, an attacker can bypass intended data isolation boundaries and access sensitive information associated with LinkedAccounts or defined Managers within the identity management system. The impact is severe because it potentially exposes hashed credentials alongside other personally identifiable information, thereby compromising the confidentiality integrity of the entire directory service infrastructure managed by Apache Syncope.
From a technical perspective, this vulnerability stems from improper neutralization of special elements used in an object graph traversal context, which aligns with CWE-915: Improper Control of Dynamically-Identified Variables. The core issue lies in how JEXL expressions are evaluated when processing derived schema definitions. When an administrator creates a new or modifies an existing Derived Schema entry, they can inject code that executes arbitrary Java methods during the serialization process. If another administrator with read permissions for User entities triggers the evaluation of these schemas, the injected expression is executed within the context of the application server. This execution allows the attacker to traverse object references beyond their intended scope, accessing private fields and properties of related objects such as LinkedAccount or Manager entries that would otherwise be inaccessible through standard API calls.
The operational impact of this vulnerability extends beyond simple data leakage. The ability to retrieve hashed credentials poses a significant risk for offline cracking attacks if those hashes are exfiltrated from the database or logs. Furthermore, access to LinkedAccount details may reveal external system connections and authentication mechanisms, providing an attacker with valuable intelligence for lateral movement within the organization's identity ecosystem. This flaw effectively undermines the principle of least privilege by allowing users with limited administrative rights to escalate their influence over sensitive data stores through code injection techniques rather than direct permission grants. The vulnerability affects multiple versions of Apache Syncope, specifically impacting releases from 3.0.0-M0 through 3.0.16 and from 4.0.0-M0 through 4.0.7, as well as the 4.1.x branch up to version 4.1.2.
In terms of threat modeling, this vulnerability can be mapped to ATT&CK technique T1558: Steal or Forge Authentication Certificates and Credentials, specifically under the sub-technique of stealing stored credentials via application layer attacks. It also relates to T1078: Valid Accounts, as it requires an authenticated administrator with specific entitlements to execute the malicious payload. The attack vector is primarily remote if the administrative interface is exposed to untrusted networks, but local exploitation is possible for any user who has been granted Derived Schema management privileges. This highlights a common challenge in enterprise identity and access management systems where powerful configuration tools can inadvertently become vectors for data exfiltration if input validation and output encoding are not rigorously enforced during expression evaluation.
To mitigate this vulnerability, organizations running affected versions of Apache Syncope must upgrade to version 4.0.8 or 4.1.3 immediately. These releases contain patches that restrict the execution context of JEXL expressions within derived schemas, ensuring that only safe and predefined methods are accessible during object graph traversal. In addition to upgrading, administrators should review existing Derived Schema configurations for any suspicious entries containing complex expression logic. Implementing strict role-based access control policies is also recommended; specifically, limiting the number of users who possess entitlements to create or modify derived schemas reduces the attack surface significantly. Regular audits of administrative actions and monitoring for unusual patterns in schema modifications can further enhance detection capabilities against such insider threats or compromised accounts.