The Apache Struts framework uses I18NInterceptor to allow users and developers switch language used in the framework and an application built on top of it. The problem is that the interceptor doesn't perform any validation of the user input and accept arbitrary string which can be used by a developer to display language selected by the user. However, the framework doesn't expose the value directly in UI. External references: http://struts.apache.org/docs/s2-030.html
Statement: A previous statement by Red Hat related to this CVE, prior to August 2019, said that Apache Struts 2 is not included in any Red Hat products. This earlier statement was incorrect. While Struts 2 is not actively compiled, shipped, used, or enabled in any Red Hat provided final products, and does not cause any vulnerability in the product, struts2-core jars have been included in some products' source code packages. The inclusion was part of an import of the Google Guice repository, which includes struts2-core. Customers that build artefacts from our source code could be at risk. Red Hat will remove these artefacts from source code in future releases. The products that included the Struts 2 artefacts in their source jars: Fuse Service Works 6.0.0 Single Sign On 7.3.0+ If you have used the source package from one of these products to build artefacts on your system, you should do the following to remove potentially affected jars: 1. Run 'find . -name struts2*.jar' under the source location 2. Remove any files found This will not affect the product, as the jar is included with the source of google-guice, but no functionality requiring struts2 is implemented.