CVE-2021-43980 : What You Need to Know

Apache Tomcat: Information disclosure.

Understanding CVE-2021-43980

An information disclosure vulnerability in Apache Tomcat versions 8.5.0 to 10.1.0-M12 which could potentially lead to sharing responses with the wrong client.

What is CVE-2021-43980?

The implementation of blocking reads and writes in certain versions of Apache Tomcat exposed a concurrency bug allowing client connections to share responses erroneously.

The Impact of CVE-2021-43980

Attackers could intercept sensitive information by receiving responses meant for other clients.
This vulnerability can result in data leakage and potentially compromise user privacy.

Technical Details of CVE-2021-43980

A detailed look into the technical aspects of the CVE

Vulnerability Description

The vulnerability allowed for the sharing of Http11Processor instances, causing responses to be sent to incorrect clients.

Affected Systems and Versions

Apache Tomcat versions 10.1.0-M1 to 10.1.0-M12
Apache Tomcat versions 10.0.0-M1 to 10.0.18
Apache Tomcat versions 9.0.0-M1 to 9.0.60
Apache Tomcat versions 8.5.0 to 8.5.77

Exploitation Mechanism

By leveraging the concurrency bug, attackers could intercept and view responses intended for other clients, potentially compromising data privacy.

Mitigation and Prevention

Steps to address and prevent the vulnerability

Immediate Steps to Take

Update Apache Tomcat to the latest patched version immediately after release.
Monitor network activity for any signs of unauthorized access.
Implement network segmentation to limit the impact of potential data leaks.

Long-Term Security Practices

Regularly update and patch all software and applications in your environment.
Conduct periodic security audits and penetration testing to identify vulnerabilities.

Patching and Updates

Stay informed about security advisories and updates from Apache Tomcat.
Apply patches promptly to mitigate the risk of data leakage and information disclosure.