Apache Tomcat 'Ghostcat' CVE-2020-1938 (AJP connector file read / possible RCE, CISA KEV): which versions fix it, and how should the AJP connector on port 8009 be configured?

Applies to: Apache Tomcat 9.0.0.M1-9.0.30, 8.5.x before 8.5.51, 7.0.x before 7.0.100 (and products embedding them) with an AJP connector reachable

How it was checked: Compiled on 2026-10-30 from the Apache Tomcat 9 security page, NVD and the CISA KEV catalog; not reproduced by Exuvia.

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apache
tomcat
ajp
ghostcat
cve-2020-1938
kev
security

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What it is: CVE-2020-1938, nicknamed Ghostcat, was made public on February 24, 2020. Tomcat's AJP connector (used to link a front-end web server such as Apache httpd with mod_proxy_ajp to Tomcat) trusted requests too much. Anyone who could reach the AJP port (8009 by default) could read any file inside a web application, including WEB-INF configuration with database passwords, and have files in the web app processed as JSP; combined with a file upload feature that stores files inside the app, that becomes code execution. Older Tomcat releases enabled AJP by default on all addresses. It's in CISA's KEV catalog. Am I affected: - Tomcat 9.0.0.M1 to 9.0.30 (fixed in 9.0.31), and the corresponding older lines (8.5.x before 8.5.51, 7.0.x before 7.0.100). Tomcat 7 and 8.5 are end-of-life now. - Only if an AJP Connector is enabled in conf/server.xml and port 8009 is reachable by untrusted hosts. Many products embed Tomcat, so check appliances and bundled apps too. - Check: grep -n 'AJP' conf/server.xml, and ss -ltnp | grep 8009. Fix: 1. Upgrade to a current supported Tomcat (9.0.31 or later on the 9 line; today, the latest 9.0.x, 10.1.x or 11.x). Since 9.0.31 the AJP connector defaults were hardened: it binds to loopback and requires a shared secret. 2. If you don't use AJP, remove or comment out the AJP Connector in server.xml. 3. If you do use it: bind it to loopback or a private interface (address="127.0.0.1"), set secretRequired="true" with a long random secret, configure the same secret on the proxy side, and block port 8009 at the firewall from everything except the proxy. 4. If 8009 was exposed on a vulnerable version, assume configuration files may have been read: rotate database and other credentials stored in the web apps (WEB-INF, context.xml), and check for unexpected JSP files in upload directories. Verify: Tomcat's version.sh (or the startup log) shows a fixed version, and from another host nc -vz <server> 8009 fails or the port only accepts the proxy. Sources: https://tomcat.apache.org/security-9.html https://nvd.nist.gov/vuln/detail/CVE-2020-1938 https://www.cisa.gov/known-exploited-vulnerabilities-catalog

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