CVE-2025-63690: Pig4cloud Pig RCE Vulnerability

CVE-2025-63690 Overview

CVE-2025-63690 is a critical remote code execution vulnerability affecting pig-mesh Pig versions 3.8.2 and below. The vulnerability exists in the Quartz management function within the system management module, where improper input validation allows attackers to execute arbitrary Java classes through reflection. By leveraging Tomcat's built-in jakarta.el.ELProcessor class and its eval method, authenticated attackers with high privileges can achieve full remote code execution on the target system.

Critical Impact

Authenticated attackers can execute arbitrary commands on affected servers, potentially leading to complete system compromise, data exfiltration, and lateral movement within the network.

Affected Products

• pig4cloud Pig versions 3.8.2 and below
• Systems using the Quartz management function in pig-mesh Pig
• Deployments running on Tomcat with the jakarta.el.ELProcessor class available

Discovery Timeline

• 2025-11-07 - CVE-2025-63690 published to NVD
• 2025-12-08 - Last updated in NVD database

Technical Details for CVE-2025-63690

Vulnerability Analysis

This vulnerability is classified as CWE-470 (Use of Externally-Controlled Input to Select Classes or Code), which occurs when the application allows external input to determine which classes are instantiated or which methods are invoked. In the context of pig-mesh Pig, the Quartz scheduler management interface fails to properly validate user-supplied input when configuring scheduled tasks.

The attack leverages Java reflection capabilities to instantiate arbitrary classes that have parameterless constructors and invoke their methods with String parameters. This is particularly dangerous because Tomcat's jakarta.el.ELProcessor class meets these criteria and provides an eval method that can execute arbitrary Expression Language expressions, which in turn can be used to execute system commands.

Root Cause

The root cause of this vulnerability lies in the unsafe use of reflection within the Quartz management functionality. The application does not implement a whitelist of allowed classes or methods that can be invoked through the scheduler configuration. Instead, it permits user-controlled input to directly influence the reflection-based class instantiation and method invocation process, creating a direct path to code execution.

Attack Vector

The attack requires network access and high-level privileges within the application. An attacker with administrative access to the system management module can configure a malicious scheduled task that specifies jakarta.el.ELProcessor as the target class and provides a crafted Expression Language payload to the eval method. When the scheduled task executes, the malicious payload runs with the privileges of the application server.

The exploitation flow involves:

1. Authenticating to the pig-mesh Pig administrative interface
2. Navigating to the Quartz management function under system management
3. Creating a scheduled task that leverages reflection to invoke jakarta.el.ELProcessor.eval()
4. Passing a malicious EL expression that executes system commands

For detailed technical information on the exploitation mechanism, refer to the vulnerability writeup on GitHub.

Detection Methods for CVE-2025-63690

Indicators of Compromise

• Unexpected scheduled tasks created in the Quartz management interface referencing jakarta.el.ELProcessor or similar reflection-capable classes
• Unusual process spawning from the Tomcat/Java application server process
• Log entries showing reflection-based class instantiation attempts with suspicious class names
• Network connections originating from the application server to unexpected external hosts

Detection Strategies

• Monitor application logs for scheduled task creation events that reference potentially dangerous Java classes
• Implement SIEM rules to alert on process creation events where the parent process is the Java application server
• Review Quartz job configurations for any tasks referencing reflection-capable classes like ELProcessor, ScriptEngine, or ProcessBuilder
• Deploy runtime application self-protection (RASP) to detect and block reflection-based attacks

Monitoring Recommendations

• Enable verbose logging for the Quartz scheduler component to capture all task configuration changes
• Implement file integrity monitoring on application configuration directories
• Monitor for unusual network traffic patterns from application servers, particularly outbound connections on non-standard ports
• Set up alerts for any modification to scheduled tasks by non-service accounts

How to Mitigate CVE-2025-63690

Immediate Actions Required

• Upgrade pig-mesh Pig to a version newer than 3.8.2 that addresses this vulnerability
• Audit existing Quartz scheduled tasks for any suspicious or unauthorized configurations
• Restrict access to the system management module to only essential administrative personnel
• Implement network segmentation to limit the blast radius of potential compromise

Patch Information

Organizations should monitor the pig-mesh Pig GitHub repository for official patch releases. Until a patch is available, implementing the workarounds below is strongly recommended. Review the external references for the latest vendor communications regarding this vulnerability.

Workarounds

• Implement an application-level whitelist of allowed classes that can be specified in scheduled task configurations
• Disable or restrict access to the Quartz management function if not required for business operations
• Deploy a Web Application Firewall (WAF) rule to block requests containing references to dangerous classes like jakarta.el.ELProcessor
• Implement additional authentication requirements (such as MFA) for accessing the system management module

# Example: Restrict access to Quartz management endpoints via reverse proxy
# Add to nginx configuration to limit access by IP
location /admin/quartz {
    allow 10.0.0.0/8;
    deny all;
    proxy_pass http://backend;
}