CVE-2026-77147: Apache Syncope Code Injection RCE Vulnerability

CVE-2026-77147 Overview

CVE-2026-77147 is a code injection vulnerability in Apache Syncope that allows an authenticated administrator to bypass the Groovy security sandbox. The flaw resides in the handling of Groovy Command classes within the Implementations feature. An administrator with sufficient entitlements can craft a malicious Groovy Command class that embeds untrusted code inside the CommandArgs static implementation, evading sandbox restrictions and executing arbitrary code within the Syncope server context [CWE-94].

Critical Impact
A high-privileged administrator can execute arbitrary Groovy code on the Apache Syncope server by bypassing the built-in security sandbox, compromising the confidentiality and integrity of identity data managed by Syncope.

Affected Products

Apache Syncope 3.0.0-M0 through 3.0.16
Apache Syncope 4.0.0-M0 through 4.0.7
Apache Syncope 4.1.0-M0 through 4.1.2

Discovery Timeline

2026-09-14 - CVE-2026-77147 published to NVD
2026-09-14 - Last updated in NVD database

Technical Details for CVE-2026-77147

Vulnerability Analysis

Apache Syncope exposes an Implementations feature that allows administrators to define custom logic using Groovy. To reduce risk, Syncope wraps Groovy execution in a security sandbox that restricts access to sensitive APIs. CVE-2026-77147 shows this sandbox does not fully cover code placed in the CommandArgs static implementation of a Groovy Command class.

An administrator with the entitlements required to create or modify Implementations can supply a Groovy Command whose CommandArgs static block contains attacker-controlled code. When Syncope loads and initializes the class, the untrusted code runs outside the sandbox boundary. This yields code execution with the privileges of the Syncope process and access to identity, credential, and workflow data managed by the platform.

The issue is authenticated and requires high privileges, which limits opportunistic exploitation. However, it is relevant in scenarios involving compromised administrator accounts, insider abuse, or delegated administration models where lower-trust operators hold Implementations entitlements.

Root Cause

The root cause is incomplete enforcement of the Groovy sandbox around static initializers of Command classes. The CommandArgs static implementation is evaluated in a context that does not apply the same restrictions used for other Groovy execution paths, enabling arbitrary bytecode to run during class initialization.

Attack Vector

The attack requires network access to the Syncope administrative interface and a valid administrator session with entitlements for Implementations. The attacker registers or updates a Groovy Command Implementation containing malicious code in the CommandArgs static block. Once the Implementation is invoked or loaded, the sandbox is bypassed and the payload executes on the server. Detailed exploitation guidance is available in the Apache Security Mailing List Thread and the OpenWall OSS-Security Post.

Detection Methods for CVE-2026-77147

Indicators of Compromise

Creation or modification of Groovy Command Implementations that include non-trivial code inside CommandArgs static blocks.
Unexpected outbound network connections, file writes, or process launches originating from the Apache Syncope JVM process.
Audit log entries showing Implementation changes by administrator accounts that do not normally manage custom logic.

Detection Strategies

Review Syncope audit logs for Implementation create and update events and correlate them with the source administrator account.
Perform static review of stored Groovy Implementations, flagging static initializers that invoke reflection, class loading, Runtime, ProcessBuilder, or network APIs.
Monitor JVM behavior for anomalies such as new child processes or unexpected socket activity that could indicate sandbox escape.

Monitoring Recommendations

Forward Syncope application and audit logs to a centralized analytics platform and alert on Implementation changes outside change windows.
Baseline normal Groovy Implementation content and alert on deltas that introduce dynamic code execution primitives.
Track administrator entitlement assignments for Implementations and alert when new accounts receive this privilege.

How to Mitigate CVE-2026-77147

Immediate Actions Required

Upgrade Apache Syncope to version 4.0.8 or 4.1.3, which remediate the sandbox bypass.
Inventory existing Groovy Command Implementations and remove or rewrite any that contain untrusted logic in CommandArgs static blocks.
Restrict the Implementations entitlement to a minimal set of trusted administrators and require multi-factor authentication for those accounts.

Patch Information

The Apache Syncope project has released fixed versions 4.0.8 and 4.1.3. Users on the 3.0.x branch should plan migration to a supported fixed release, as versions 3.0.0-M0 through 3.0.16 are listed as affected. See the Apache Security Mailing List Thread for release details.

Workarounds

Temporarily revoke the Implementations entitlement from all administrator roles until patching is complete.
Place the Syncope administrative console behind a VPN or IP allowlist to limit exposure of the authenticated attack surface.
Enable strict change control and peer review for any new or modified Groovy Implementation before deployment.

bash

# Configuration example: verify installed Apache Syncope version
curl -s -u <admin>:<password> \
  https://syncope.example.com/syncope/rest/syncope/info | \
  grep -i version

# Expected fixed versions: 4.0.8 or 4.1.3