Apache Syncope Groovy RCE Vulnerability Allows Attackers Inject Malicious Code

Apache Syncope has disclosed a critical security flaw that enables authenticated administrators to execute arbitrary code on affected systems.

Tracked as CVE-2025-57738, this vulnerability impacts all Apache Syncope versions 3.x before 3.0.14 and 4.x before 4.0.2, exposing organizations to potentially devastating system compromise through malicious Groovy code injection.

Vulnerability Overview

The flaw resides in Syncope’s custom implementation engine, which allows administrators to extend core functionality by uploading Java or Groovy code.

While Java extensions require precompiled JAR files, Groovy scripts can be submitted as plain source code and compiled at runtime to support hot-reloading.

Unpatched versions use a plain GroovyClassLoader to compile and execute these scripts without any sandbox restrictions or security controls.

As a result, any administrator with permission to create or update Groovy implementations can inject scripts that the server runs with full privileges of the Syncope Core process.

Exploitation requires valid administrator or delegated-administrator credentials within a Syncope tenant.

An attacker uploads a Groovy script via the REST API endpoints for report definitions or direct implementation updates.

Because the code compiles and runs without safety checks, the script can perform actions such as executing shell commands, reading or writing files on the server, inspecting environment variables, and making network connections.

Proof-of-concept exploits demonstrate simple commands like creating marker files with Runtime.exec, as well as more advanced attacks using ProcessBuilder to spawn interactive shells.

All operations occur under the operating system user account running Syncope, often named syncope or a generic container user.

Successful exploitation grants attackers full control over the Syncope deployment.

They can exfiltrate sensitive data, including credentials and configuration secrets, modify or delete critical files, and potentially move laterally within the hosting environment depending on network segmentation and container isolation.

Because the vulnerability demands privileged access, it poses a heightened threat when administrator credentials are compromised or misused by insiders.

Apache has addressed CVE-2025-57738 by releasing patched versions 3.0.14 and 4.0.2, which incorporate a Groovy sandbox that blocks dangerous operations.

This sandbox restricts APIs like Runtime.exec, ProcessBuilder, and unrestricted file I/O. Organizations should upgrade immediately to these patched releases and verify that no legacy instances remain online.

Security teams are advised to:

• Review HTTP logs for POST requests to /syncope/rest/implementations and PUT requests updating implementations that specify the GROOVY engine.
• Monitor report creation and execution activities for unexpected entries.
• Enable filesystem auditing to detect newly created or altered files under the Syncope installation path.
• Observe process trees for unusual child processes spawned by the Syncope Java process.

By combining timely patching with targeted log analysis and system monitoring, organizations can effectively defend against this dangerous Groovy code injection vulnerability.

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