This blog post discusses a real-world example of a Stored Cross-Site Scripting (Stored XSS) vulnerability that bypassed a blacklist-based Web Application Firewall (WAF). Despite the WAF indicating that the malicious payload was blocked, the crafted XSS payload was successfully stored in the target application and executed, revealing the bypass. The post provides a full walkthrough of how the bypass was achieved and why the blacklist approach used by the WAF was insufficient to detect and stop this particular payload. It emphasizes the risks associated with relying solely on blacklist-based WAFs for protecting web applications against sophisticated XSS attacks. The example serves as a reminder for bug bounty hunters and cybersecurity professionals about the need for robust WAF configurations and additional layers of defense to mitigate Stored XSS threats effectively.
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