Vert.x-Web is a set of building blocks for building web applications in the java programming language. When running vertx web applications that serve files using StaticHandler on Windows Operating Systems and Windows File Systems, if the mount point is a wildcard (*) then an attacker can exfiltrate any class path resource. When computing the relative path to locate the resource, in case of wildcards, the code: return "/" + rest; from Utils.java returns the user input (without validation) as the segment to lookup.

Even though checks are performed to avoid escaping the sandbox, given that the input was not sanitized \ are not properly handled and an attacker can build a path that is valid within the classpath. This issue only affects users deploying in windows environments and upgrading is the advised remediation path. There are no known workarounds for this vulnerability.