&gt;And how did a PNG file ever pass through the PHP interpreter?<p>It is possible if you do something stupid like blindly including or requiring the &quot;image&quot; file content, as part of serving the image through a PHP file. Anything run through include() or require() is run through the parser if it contains php tags. I vaguely remember it being an issue with user avatars in one of the more popular PHP forums but I don&#x27;t remember which.<p>It&#x27;s one of those things where even though you <i>can</i> do it that way in PHP, it basically takes a comedy of errors (or just a malicious plugin writer) for it to even occur.