This tweet is about bypassing or creating custom firewall rules in the context of Vercel's hosting platform. The user is asking how to create a system bypass firewall rule for a project on Vercel, but they face difficulties because the firewall setup requires a CIDR range to specify allowed traffic sources. However, they can't find the CIDR ranges used by Vercel hosted projects. They propose a possible workaround involving creating a custom WAF rule that matches based on the host header or the user-agent string, which could allow traffic through without needing CIDR ranges.
In simple terms, the user wants to bypass or customize the firewall rule for another project on Vercel but is limited by the firewall's requirement to specify network ranges (CIDR). The suggested approach is to use different HTTP characteristics, like host or user-agent, to allow certain traffic instead.
This is not about bypassing a traditional WAF vulnerability like XSS or SQLi filtering but is more about user-configured firewall rules in a cloud hosting environment, specifically Vercel. It highlights challenges in configuring firewall rules when source IP ranges are not well-defined or known.
For more insights, check out the original tweet here: https://twitter.com/oieduardorabelo/status/1960331404123984116