10

The title pretty much says it all. It seems counter-intuitive to escape inside a <noscript> block because any js that an attacker is able to inject there shouldn't be executed. But, I'm still pretty new to this, so I thought it would be prudent to ask.

For clarity, this is the context that I'm talking about:

<noscript>
<img src="<?php echo 'Should I escape this url' ?>" />
</noscript>
16

Yes. You should always escape untrusted data. Here's an attack for your snippet (pseudocode):

<noscript>
<img src="<?php echo 'you should always escape everything, 
                dependeing on the context. This context is url in an attribute, 
                you should escape it appropriately. otherwise " />
                </noscript> 
                <script>alert("you will be vulnerable")</script><noscript><img "' ?>" />
</noscript>
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  • Thanks for the explanation and the helpful code. It seems pretty obvious now. :) – Dominic P Jan 13 '14 at 20:20

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