Improper validation of resource URL attributes allows an unauthenticated remote attacker to read files from the web application, including files under WEB-INF that the servlet container would not otherwise serve. The locale, style, and variation attributes decoded from a package resource URL are spliced into the resource lookup path without being checked for path separators. Because the `IPackageResourceGuard` and `WebApplicationPath` do not inspect the attacker-controlled portion of the path, a crafted request can escape the intended package directory on servlet containers that normalize `..` in `ServletContext.getResource()`. The readable files are limited to extensions permitted by the configured `IPackageResourceGuard`. Applications using the blocklist-based `PackageResourceGuard` or custom patterns may disclose configuration files such as `web.xml`. Additionally, the lookup process can act as an existence oracle for arbitrary paths.