FreshRSS vulnerable to favicon cache poisoning via proxy

FreshRSS is a self-hosted RSS feed aggregator. Prior to version 1.26.2, it's possible to poison feed favicons by adding a given URL as a feed with the proxy set to an attacker-controlled one and disabled SSL verifying. The favicon hash is computed by hashing the feed URL and the salt, whilst not including the following variables: proxy address, proxy protocol, and whether SSL should be verified. Therefore it's possible to poison a favicon of a given feed by simply intercepting the response of the feed, and changing the website URL to one where a threat actor controls the feed favicon. Feed favicons can be replaced for all users by anyone. Version 1.26.2 fixes the issue.