I saw this weird warning in Chrome’s DevTools while looking at a site:
OTS parsing error: invalid version tag
Uh-huh. That’s a bit strange. Unable to download fonts? What caused that?
Well, I tried going to the font’s URL – and got the ‘Page Not Found’ page! Well, that’s annoying – but a 404 page is clearly not a font.
However, this site’s error pages return HTTP 200 – so Chrome expects a font…
Make sure your error pages return a correct HTTP status code. If you don’t, it can cause problems. Normally, I find that it’s false positives on automated penetration tests, but this is a new and exciting variation.