Improve image handling in markdown statements #318
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Support images in subdirectories (statement/img/foo.png linked as img/foo.png) Add more security-focused checks on what img_src we allow
pehrsoderman
approved these changes
May 21, 2025
| @@ -1,3 +1,3 @@ | |||
| Make web request via image | |||
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| <img src="http:picsum.photos/400"> | |||
| <img src="https:open.kattis.com/images/site/header/logo-empty.png"> | |||
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What's up with the lack of // here?
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This tests for a (mild) vulnerability that existed previously where a markdown statement could link to an external image (per the text two lines above). The link https:open.kattis.com/images/site/header/logo-empty.png will be interpreted by a browser as a normal https link, as if the // was there. However, it's also a valid relative path on a unix system, and that files exists in a subdirectory to this file.
We want to make sure images are all contained in problem packages and that the rendered markdown does not allow images to be loaded external sites (even if the problem packager is malicious and drops a suitably named file).
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statement/img/foo.pnglinked asimg/foo.png)imgsrctags we allowThanks to @Matistjati for finding these errors