CVE-2025-6811 Overview
CVE-2025-6811 is a critical insecure deserialization vulnerability affecting Mescius ActiveReports.NET that allows remote attackers to execute arbitrary code on affected installations. The vulnerability exists within the TypeResolutionService class, where improper validation of user-supplied data enables deserialization of untrusted data, leading to remote code execution in the context of the current process.
This vulnerability was discovered through the Zero Day Initiative (ZDI) program and tracked as ZDI-CAN-25397. While interaction with the ActiveReports.NET library is required for exploitation, attack vectors may vary depending on the specific implementation within target applications.
Critical Impact
Remote attackers can achieve arbitrary code execution by exploiting the deserialization flaw in the TypeResolutionService class, potentially leading to complete system compromise.
Affected Products
- Mescius ActiveReports.NET version 18.1.1
- Applications implementing the ActiveReports.NET library
Discovery Timeline
- 2025-07-07 - CVE-2025-6811 published to NVD
- 2025-08-14 - Last updated in NVD database
Technical Details for CVE-2025-6811
Vulnerability Analysis
This insecure deserialization vulnerability (CWE-502) resides in the TypeResolutionService class within Mescius ActiveReports.NET. The flaw enables remote code execution through a network-accessible attack vector that requires no authentication or user interaction to exploit.
The vulnerability stems from the application's failure to properly validate user-supplied data before deserialization operations. When untrusted data is passed to the TypeResolutionService class, the deserialization process can be manipulated to instantiate arbitrary objects and execute malicious code within the context of the running process.
ActiveReports.NET is a widely-used .NET reporting library, and applications integrating this component may expose the vulnerability through various implementation-specific attack surfaces. The network-accessible nature of this flaw significantly increases its risk profile for organizations using affected versions in web-facing applications or services.
Root Cause
The root cause is the absence of proper input validation in the TypeResolutionService class before deserializing user-controlled data. The class accepts and processes untrusted serialized objects without verifying their integrity or origin, allowing attackers to craft malicious payloads that execute arbitrary code during the deserialization process.
.NET deserialization vulnerabilities are particularly dangerous because they can lead to immediate code execution when the application deserializes a specially crafted object. The TypeResolutionService class appears to resolve types dynamically without appropriate security controls, enabling type confusion attacks that instantiate dangerous gadget chains.
Attack Vector
The attack vector is network-based, requiring no privileges or user interaction. An attacker can exploit this vulnerability by sending a specially crafted serialized payload to an application that uses the vulnerable TypeResolutionService class.
The exploitation technique typically involves crafting a malicious serialized object containing a gadget chain that, when deserialized, triggers arbitrary code execution. Common .NET deserialization gadget chains leverage types from the .NET Framework itself or common third-party libraries to achieve code execution.
For detailed technical information about this vulnerability, see the Zero Day Initiative Advisory ZDI-25-449.
Detection Methods for CVE-2025-6811
Indicators of Compromise
- Unexpected process spawning from applications using ActiveReports.NET
- Anomalous network connections originating from .NET application processes
- Unusual serialized data payloads in application logs or network traffic
- Memory corruption or application crashes related to deserialization operations
Detection Strategies
- Monitor for known .NET deserialization gadget chain patterns in network traffic
- Implement application-level logging for deserialization events in TypeResolutionService
- Deploy endpoint detection rules targeting post-exploitation behaviors following deserialization attacks
- Review application logs for exceptions or errors related to type resolution failures
Monitoring Recommendations
- Enable verbose logging for applications using ActiveReports.NET to capture deserialization events
- Configure SIEM rules to alert on suspicious .NET serialization patterns in network traffic
- Monitor process behavior for applications using the affected library, particularly child process creation
- Implement network segmentation to limit exposure of applications using vulnerable components
How to Mitigate CVE-2025-6811
Immediate Actions Required
- Identify all applications in your environment using Mescius ActiveReports.NET version 18.1.1
- Prioritize patching for internet-facing applications that implement the vulnerable library
- Implement network-level controls to restrict access to affected applications until patching is complete
- Review application architecture to identify potential attack surfaces exposing the TypeResolutionService class
Patch Information
Consult the Zero Day Initiative Advisory ZDI-25-449 for current patch availability and remediation guidance from Mescius. Organizations should update to the latest patched version of ActiveReports.NET as soon as it becomes available.
Workarounds
- Implement input validation and sanitization before data reaches deserialization functions
- Consider implementing a type allowlist to restrict which types can be deserialized
- Apply network segmentation to limit exposure of applications using vulnerable components
- Deploy Web Application Firewall (WAF) rules to detect and block common deserialization payloads
# Example: Review applications for ActiveReports.NET usage
# Scan for assemblies referencing the vulnerable component
find /path/to/applications -name "*.dll" -exec grep -l "GrapeCity.ActiveReports" {} \;
# Monitor for suspicious .NET serialization activity in logs
grep -i "TypeResolutionService\|deserialization\|BinaryFormatter" /var/log/application/*.log
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
