Apache Syncope Groovy RCE Vulnerability Let Attackers Inject Malicious Code

Apache Syncope, an open-source identity management system, has been found vulnerable to remote code execution (RCE) through its Groovy scripting feature, as detailed in CVE-2025-57738.

This flaw affects versions prior to 3.0.14 and 4.0.2, where administrators can upload malicious Groovy code that runs with the full privileges of the Syncope Core process.

Discovered by security researcher Mike Cole of Mantel Group, the vulnerability stems from the lack of a sandbox environment for Groovy implementations, potentially allowing attackers to compromise entire systems.

The issue arises because Syncope lets users extend its core functionality via custom Java interfaces, which can be implemented using either Java classes or Groovy scripts for hot-reloading at runtime.

In vulnerable versions, the GroovyClassLoader compiles and executes these scripts without restrictions, exposing dangerous APIs like Runtime.exec or ProcessBuilder to untrusted input.

This design choice enables delegated administrators with access to the Implementations and Reports APIs to inject code that performs arbitrary operations on the server.

Apache Syncope Groovy RCE Vulnerability

Syncope’s architecture includes an “Implementation” abstraction for custom logic, with Groovy as one supported engine type.

Without a security manager or deny-list, uploaded Groovy code can directly invoke system-level functions, such as filesystem access or process spawning.

For instance, attackers can create a Groovy implementation of type REPORT_DELEGATE, bind it to a report, and trigger execution via REST endpoints like POST /syncope/rest/reports/{key}/execute.

This executes the code under the Syncope service account, which often runs with elevated privileges in enterprise deployments.

Reproduction involves simple HTTP requests using basic authentication, such as uploading a script that touches a marker file in /tmp to prove execution.

The vulnerability requires administrative entitlements but does not need pre-authentication, making it a high-risk insider or compromised account threat.

Execution surfaces include reports, tasks, and connectors, broadening the application’s attack paths. If hardening is weak, attackers could inspect environment variables for secrets, write files, or pivot to container hosts.

Mapped to MITRE ATT&CK, this aligns with tactics like Valid Accounts (T1078) and Command and Scripting Interpreter (T1059), enabling persistence and evasion.

Apache has addressed the issue in releases 3.0.14 and 4.0.2 by introducing a Groovy sandbox that blocks hazardous operations through classloading restrictions and policy enforcement.

Users should upgrade immediately, as binary patches are not provided, and rebuild from the source if needed. To verify the fix, attempt the same exploitation steps; sandbox violations should now log errors without executing code.syncope.

Disable Groovy engines and favor vetted Java implementations via CI/CD pipelines for interim protection on vulnerable versions.

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