1. A system comprising: a processor; and storage media accessible to the processor, the storage media including: a plurality of browsers, wherein each browser is capable of visiting network locations as represented by uniform resource locators (URLs), and wherein the plurality of browsers includes a lower patched browser version and a higher patched browser version; and a browser-based vulnerability exploit detector to: direct the lower patched browser version to visit a given URL; determine whether the given URL accomplishes an exploit in conjunction with the lower patched browser version; direct the higher patched browser version to visit the given URL in response to the given URL accomplishing a particular exploit in conjunction with the lower patched browser version; determine if the given URL accomplishes an exploit in conjunction with the higher patched browser version; and determine that the particular exploit assaults a vulnerability remedied by a patch for the higher patched browser version when the given URL does not accomplish an exploit in conjunction with the higher patched browser version.