It's referring to a Web Application Firewall.

Because enterpise firewalls suck ass. If you follow some security researchers on fedi it is shockingly common. Like every week there is an unauth RCE to these things and usually its ../. Is it absurd that a companies expensive first line defense is less secure than your mum's laptop? I'm sure it is "AI" ready though!

The point of the comic is that people expect a firewall to protect them from attacks, but then the attack comes in as a path traversal and the firewall does nothing.

Frankly to suggest that an enterprise firewall would be susceptible to a simple path traversal attack is insane. Unless there's the most embarrassing news story of the decade im missing? That kind of input validation is baked into basically everything these days.

Maybe you'll land input validation using quadruple URL encoded '../' or something but even still I'd doubt that.

So the person who replied to you is 100% correct in what it's about, but it doesn't really explain the comic. Unless it was made in like a decade ago.

Layer 7 firewalls are a thing