In response to 0.0.0.0 day, Firefox Nightly version 131 had introduced a new security measure: blocking access to 0.0.0.0/::/::ffff:0.0.0.0 addresses. This change is currently live for Nightly users and will be gradually rolled out to all release users in the near future. Before we implement this ch...
The first hyperlink in that post explains exactly why:
https://www.oligo.security/blog/0-0-0-0-day-exploiting-localhost-apis-from-the-browser
Oh man, I thought, it was some silly celebration day for the 0.0.0.0 address, so I didn’t even click on the link at first.