JAI-EXT is an open-source project which aims to extend the Java Advanced Imaging (JAI) API. Programs allowing Jiffle script to be provided via network request can lead to a Remote Code Execution as the Jiffle script is compiled into Java code via Janino, and executed. In particular, this affects the downstream GeoServer project. Version 1.2.22 will contain a patch that disables the ability to inject malicious code into the resulting script. Users unable to upgrade may negate the ability to compile Jiffle scripts from the final application, by removing janino-x.y.z.jar from the classpath.

Improper Control of Generation of Code ('Code Injection') in jai-ext