Medium [CVE-2026-84177] Incorrect behavior order in Apache Wicket: a file path is validated before the framework appends the attributes that complete it

Incorrect behavior order in Apache Wicket: a file path is validated before the framework appends the attributes that complete it.

org.apache.wicket.request.resource. PackageResource asks the configured package resource guard about a path built from the scope class' package and the file name in the request URL, and then hands that same path to the resource stream locator together with a style, a variation and a locale.

ResourceNameIterator appends them to that path, each preceded by an underscore, in the order variation, style, locale, before the file extension, so the file that is opened is not the file the guard approved.

org.apache.wicket.markup.html. PackageResourceGuard decides whether an HTML file is a component's markup template by looking for a class file of the same name beside it, stripping one underscore-delimited suffix at a time as it goes.

HTML is on the default allow list, so that check is the only thing separating a static HTML file, which may be served, from a markup template, which may not. Asked about the name of a template, the guard refuses it correctly.

Asked about a shorter name for which no class exists, it accepts, and a style supplied in the URL then completes that name into the markup template of a component class, which is written to the response.