This tweet mentions a bypass for Vercel's Web Application Firewall (WAF). The user indicates that a previously known vulnerability or bypass was patched, but they managed to bypass the Vercel WAF again with the same or similar technique, as the bypass slipped through the protections. Unfortunately, the tweet does not provide the specific type of vulnerability the bypass targets (such as XSS, SQLi, RCE, etc.) or the exact payload used for the bypass. The important context is that Vercel's WAF was initially patched, yet this user successfully circumvented it, demonstrating a weakness or gap in the patch or the WAF's filtering rules. Such bypasses highlight the challenges in securing applications with WAFs, as attackers often find new or modified methods to evade detection and blocking. Researchers and developers must continuously test and update WAF rules to keep pace with emerging bypass techniques.
For more details, check out the original tweet here: https://twitter.com/broken_link420/status/1997665089101389839