Possible Cross-Site Scripting Vulnerability

[tch1bo]

Hey,

I noticed a possible XSS (https://www.owasp.org/index.php/Cross-site_Scripting_(XSS)) vulnerability in line: https://github.com/kylewm/silo.pub/blob/46aece85f8918f56ed75f1e11b544c10f70a17fc/silopub/micropub.py#L107

Unsanitized user input gets into flask.make_response() and then into user's browser. This opens a possibility for the attacker to supply input like "" and execute arbitrary code in user's browser.

I'm not sure how your application is meant to be deployed, but if an attacker may trick an honest user to access "your_site.com/indieauth?redirect_uri=foo&me=attack_vector", then this is a security risk and you should consider fixing it.

Cheers!