CVE-2025-5552 Overview
CVE-2025-5552 is a deserialization vulnerability affecting ChestnutCMS versions up to 15.1. The flaw resides in the /dev-api/groovy/exec API endpoint, where untrusted input is processed without adequate validation. Attackers can exploit this issue remotely over the network with low-privilege authentication. The vulnerability has been publicly disclosed, increasing the likelihood of exploitation attempts against exposed instances.
ChestnutCMS is an open-source content management system maintained by 1000mz. The exposed Groovy execution endpoint allows manipulation of serialized data structures, which can compromise the confidentiality, integrity, and availability of the affected application.
Critical Impact
Remote attackers with low privileges can trigger unsafe deserialization through the Groovy execution endpoint, leading to potential code execution and full application compromise.
Affected Products
- 1000mz ChestnutCMS versions up to and including 15.1
- ChestnutCMS deployments exposing the /dev-api/groovy/exec API endpoint
- Web applications built on the vulnerable ChestnutCMS framework
Discovery Timeline
- 2025-06-04 - CVE-2025-5552 published to NVD
- 2025-11-18 - Last updated in NVD database
Technical Details for CVE-2025-5552
Vulnerability Analysis
The vulnerability resides in the /dev-api/groovy/exec endpoint of ChestnutCMS. This component accepts data that is later deserialized by the application without sufficient validation of the input structure or type. Insecure deserialization [CWE-20] in this context allows attackers to influence the object graph reconstructed by the application.
The endpoint exposes Groovy script execution capabilities through an API surface. When combined with deserialization of attacker-controlled payloads, this design pattern enables manipulation of runtime object state. The issue is classified as an improper input validation flaw and is exploitable across the network with low attack complexity.
Root Cause
The root cause is the absence of strict input validation on data submitted to the Groovy execution endpoint. The application reconstructs objects from untrusted serialized input without enforcing class allow-lists or signature verification. This pattern is a well-known anti-pattern in Java and Groovy ecosystems, where gadget chains can be assembled to influence runtime behavior.
Attack Vector
The vulnerability is exploitable remotely over the network. An authenticated attacker with low privileges submits a crafted payload to /dev-api/groovy/exec. The endpoint processes the payload through its deserialization routine, allowing manipulation of objects that the application later acts upon. No user interaction is required to trigger the flaw.
The exploit details have been publicly disclosed through the GitHub Issue Discussion and VulDB CTI ID #311002, increasing the risk of opportunistic exploitation against internet-exposed deployments.
For exploitation specifics, refer to the public disclosure on GitHub. No verified proof-of-concept code is included here.
Detection Methods for CVE-2025-5552
Indicators of Compromise
- HTTP requests targeting the /dev-api/groovy/exec endpoint with unusually large or binary-encoded POST bodies
- Serialized Java or Groovy object headers (such as aced0005 magic bytes) appearing in request payloads to the ChestnutCMS API
- Unexpected child processes spawned by the ChestnutCMS application server, such as shell interpreters or network utilities
- Outbound network connections originating from the CMS process to unknown hosts following requests to the Groovy endpoint
Detection Strategies
- Inspect web server and application logs for POST requests to /dev-api/groovy/exec and correlate them with the source IP reputation
- Deploy web application firewall rules that flag serialized object signatures and Groovy-specific gadget patterns in request bodies
- Monitor for anomalous Groovy script invocations or reflection calls within ChestnutCMS runtime telemetry
Monitoring Recommendations
- Enable verbose logging on the ChestnutCMS API gateway and forward logs to a centralized analytics platform for retention and correlation
- Establish baseline behavior for the CMS application process and alert on deviations such as new outbound connections or unexpected file writes
- Track authentication events for low-privilege accounts that subsequently access development or administrative API endpoints
How to Mitigate CVE-2025-5552
Immediate Actions Required
- Restrict network access to the /dev-api/groovy/exec endpoint using firewall rules or reverse proxy filters
- Disable the Groovy execution endpoint in production deployments if it is not required for business operations
- Audit all ChestnutCMS user accounts and revoke unnecessary privileges, especially for accounts with API access
- Place ChestnutCMS instances behind authenticated VPN access until a patch is applied
Patch Information
No official vendor patch has been published in the references at the time of writing. Administrators should monitor the ChestnutCMS GitHub repository and VulDB entry #311002 for upstream remediation announcements. Until a patch is available, apply the workarounds below.
Workarounds
- Block all external traffic to development API paths under /dev-api/ at the perimeter
- Implement strict input validation and reject requests containing serialized object markers at the web application firewall layer
- Run the ChestnutCMS application under a least-privilege service account to limit the impact of successful exploitation
- Segment the CMS host from sensitive internal networks to contain lateral movement after compromise
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
