CitrixBleed, or CVE-2023-4966, is now an infamous security vulnerability affecting Citrix NetScaler that allows attackers to hijack user sessions by stealing session authentication tokens. Unfortunately, it has affected many NetScaler customers including Xfinity, which lost data for 36 million customers as a result of CitrixBleed. There is no way to protect against CitrixBleed by configuring the NetScaler WAF to detect and block it.