CVE-2021-42717 : Vulnerability Insights and Analysis
Discover how the ModSecurity versions 3.x through 3.0.5 and 2.8.0 through 2.9.4 mishandle deeply nested JSON objects, leading to a denial-of-service vulnerability. Learn about the impact, affected systems, and mitigation steps.
ModSecurity 3.x through 3.0.5 and Modsecurity 2.8.0 through 2.9.4 mishandle excessively nested JSON objects, leading to a denial-of-service vulnerability.
Understanding CVE-2021-42717
In this section, we will delve into what CVE-2021-42717 entails.
What is CVE-2021-42717?
ModSecurity versions 3.x through 3.0.5 and 2.8.0 through 2.9.4 mishandle deeply nested JSON objects, causing a severe impact on web server performance.
The Impact of CVE-2021-42717
Crafted JSON objects with excessive nesting can render a web server unable to process legitimate requests.
Technical Details of CVE-2021-42717
Let's explore the technical aspects of CVE-2021-42717.
Vulnerability Description
The vulnerability arises from mishandling deeply nested JSON objects by ModSecurity, impacting web server performance.
Affected Systems and Versions
- ModSecurity 3.x through 3.0.5
- Modsecurity 2.8.0 through 2.9.4
Exploitation Mechanism
- Crafted JSON objects with tens-of-thousands deep nesting
- Even moderately large HTTP requests (e.g., 300KB) can disrupt server operation
Mitigation and Prevention
Learn how to mitigate the risks associated with CVE-2021-42717.
Immediate Steps to Take
- Update ModSecurity to a patched version
- Monitor server performance for any signs of excessive CPU usage
- Implement rate limiting on incoming requests
Long-Term Security Practices
- Regularly update ModSecurity and other security tools
- Conduct security audits to identify vulnerabilities proactively
Patching and Updates
- Apply security patches promptly
- Stay informed about future vulnerabilities and updates