In a web-based environment the most attacked applications are those having direct or indirect relation to internet.
The list of such applications mostly comprised from PDF readers, digital document processors, media players and web browsers, while in case of web-browsers in addition to its internal vulnerabilities, web- browsers may also suffer from vulnerabilities found in installed plug-ins (like ActiveX or Firefox add-ons).
Here are some examples of known vulnerabilities (as named in
CVE) and their possible exploitation: