The matter at hand is Cross Site Scripting, this is protecting the user from malicious foreign content. *Mis*configuration of a server to execute images on the server is irrelevant( The only likely means for this is to have the execution bit set on the file on a UN*X server and allow execution of either any file, or files by location. Files from a Samaba share typically appear to have the execution bit set. Again though, this affects the *server*.)
perl -pew "s/\b;([mnst])/'$1/g"