CVE-2020-1938: Improper Privilege Management in Apache Tomcat AJP Connector

CVE-2020-1938, known as the Ghostcat vulnerability, represents a critical Java vulnerability in Apache Tomcat's Apache JServ Protocol (AJP) implementation with a CVSS score of 9.8. This vulnerability affects Apache Tomcat versions 9.0.0.M1 through 9.0.0.30, 8.5.0 through 8.5.50, and 7.0.0 through 7.0.99, discovered and disclosed on February 24, 2020. The vulnerability details reveal that the AJP connector, enabled by default and listening on all configured IP addresses, creates substantial exploit risk due to improper privilege management where Tomcat treats AJP connections with higher trust than HTTP connections. This trust relationship allows attackers to return arbitrary files from anywhere in the web application and process any file as a JSP, potentially leading to remote code execution when combined with file upload capabilities. The technical root cause stems from Apache Tomcat's flawed trust model for AJP connections, creating a critical attack vector for known exploited vulnerabilities. The vulnerability enables two primary attack methods: unauthorized file access throughout the web application scope and JSP processing of arbitrary files, which can escalate to remote code execution if attackers can control web application content through file uploads or other means. Major vendors including Red Hat, Debian, and Oracle issued security advisories due to the widespread impact across multiple package ecosystems. Mitigation steps require upgrading to Apache Tomcat versions 9.0.31, 8.5.51, or 7.0.100 or later, which include hardened AJP Connector configurations. For immediate protection, organizations should ensure AJP ports are not accessible to untrusted users and maintain updated CVE database records to track this critical vulnerability and similar privilege management flaws in Java applications.