I don't understand why it wasn't immediately understood that SVG is as dangerous as HTML.
It is not, and never was, an image format. It's a markup language.
I don't understand why it wasn't immediately understood that SVG is as dangerous as HTML.
It is not, and never was, an image format. It's a markup language.
Browsers already treat the same SVG differently depending on how you embed it. <img> strips scripts and external resource loads. <object> and inline don't. People test with img tags, looks fine, then someone switches the embed method and everything opens up.
it'd be nice if there was a way to declare in the URL that a given SVG could only be treated as an image so that you could safely open SVG urls, etc without exposing yourself to the dangers of embed/inline.
Couldn’t you do that using Content-Security-Policy?
If you control the domain then yes you could. But if I want to put a link on my website to some SVG hosted elsewhere and I want it to be safe for you to open that link in a new tab then there's not really a way for CSP to protect you the user from the host deploying a malicious SVG.
Like opening a PNG in a new tab is harmless but opening an SVG in a new tab is opening a pretty substantial can of worms.
If your threat model is “I don’t want the image I’m hotlinking to be replaced with something else when opened in a new tab”, then no image format is safe.
A markup language can be an image format. The "G" is for "Graphics" after all.