Wallbleed: "buffer over-read vulnerability that existed in the DNS Injection Subsystem of the Great Firewall of China ... Wallbleed caused certain nation-wide censorship middleboxes to reveal up to 125 bytes of their memory when censoring a crafted DNS Query"

https://www.ndss-symposium.org/ndss-paper/wallbleed-a-memory-disclosure-vulnerability-in-the-great-firewall-of-china/