CVE-2021-21342 is a vulnerability that affects the popular open-source Apache Tomcat web server, which can be exploited by an attacker to bypass authentication and gain access to sensitive data or perform unauthorized actions. The vulnerability is caused by an issue in the way Tomcat handles certain requests with HTTP/2 protocol enabled, allowing an attacker to send malicious requests that may lead to arbitrary file reads or writes under certain configurations.
The vulnerability was first reported on January 5th, 2021, and a patch was released by the Apache Software Foundation on February 3rd, 2021. The severity of the vulnerability is rated as medium, with a CVSS score of 6.5 out of 10. However, it should be noted that exploitation of this vulnerability requires specific configurations, so not all Tomcat instances are affected.
It is highly recommended for organizations using Apache Tomcat to update their software to the latest version as soon as possible, to avoid any potential security risks. Additionally, best practices such as regularly reviewing security advisories and keeping up-to-date with security patches can help mitigate the impact of vulnerabilities like CVE-2021-21342.