What I find strange is that I have a VPS setup on Digital Ocean, with Ubuntu LTS + OpenSSL 1.0.1 + a manually compiled Nginx. This combination should have been vulnerable, yet my website is not reported as vulnerable by the tools I tried for detecting the vulnerability.

Maybe DigitalOcean issued a fix without me noticing? I also updated my Ubuntu packages, yet OpenSSL is still at 1.0.1.