I don't think this is what OP was talking about but fonts are Turing-complete and can introduce all manner of exploits.[0] However, getting the font installed s

I don't think this is what OP was talking about but fonts are Turing-complete and can introduce all manner of exploits.[0] However, getting the font installed seems like the hard bit - I don't see how loading it or detecting it in a website makes anything new possible. [0] https://www.trendmicro.com/vinfo/us/security/news/vulnerabilities-and-exploits/microsoft-alerts-users-about-critical-font-related-remote-code-execution-vulnerability-in-windows https://www.trendmicro.com/vinfo/us/security/news/vulnerabil...