JSONView Chrome extension contains a serious security vulnerability

I was surprised that the JSONView Chrome extension wasn't working when I opened a tab with JSON that didn't get reformatted. When I checked chrome://extensions/, there was a note: "This extension contains a serious security vulnerability." The extension had been automatically disabled in Chrome.

When I googled the extension, opening the extension's page in the Chrome store returned a 404. I haven't been able to get more information about what the vulnerability is.