Anubis is a tool that allows administrators to protect bots against AI scrapers through bot-checking heuristics and a proof-of-work challenge to discourage scraping from multiple IP addresses. Anubis allows attackers to bypass the bot protection by requesting a challenge, formulates any nonce (such as 42069), and then passes the challenge with difficulty zero. Commit e09d0226a628f04b1d80fd83bee777894a45cd02 fixes this behavior by not using a client-specified difficulty value.
libX11 X library allows remote attackers to cause a denial of service via a resource mask of 0, which causes libX11 to go into an infinite loop.
libICE in XFree86 allows remote attackers to cause a denial of service by specifying a large value which is not properly checked by the SKIP_STRING macro.