http://www.perlmonks.org?node_id=166720


in reply to Re: Safe CSS Stylesheets
in thread Safe CSS Stylesheets

Style attributes (style="") do not refer to a URI, though any valid CSS setting for that element which uses a URI may be used. In this case the STYLE attribute and tag are not different.

The SRC value of an IMG tag is not the issue, whatever type of image, the browser SHOULD only handle it as an image. Although certain plugins may have co-opted control of given MIME-types (eg. QuickTime and PNG), and be exploitable. What was likely referred to is touched upon in the JavaScript discussion I linked to, IMG tags (and so many others) are allowed event attributes such as ONLOAD which can execute inlined script.

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*.)

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perl -pew "s/\b;([mnst])/'$1/g"