I stumbled across a nasty XSS hole involving DNS A records. Found out today that an old subdomain that I had assigned an IP address to via a DNS A record was serving unexpected content—turned out I’d shut down the associated VPS and the IP had been recycled to someone else, so their content was now appearing under my domain. It strikes me that if you got really unlucky this could turn into an XSS hole—and that new server could even use Let’s Encrypt to obtain an HTTPS certificate for your subdomain.
I’ve added “audit your A records” to my personal security checklist.
Recent articles
- LLM 0.27, the annotated release notes: GPT-5 and improved tool calling - 11th August 2025
- Qwen3-4B-Thinking: "This is art - pelicans don't ride bikes!" - 10th August 2025
- My Lethal Trifecta talk at the Bay Area AI Security Meetup - 9th August 2025