Vapor is a server-side Swift HTTP web framework. When using automatic content decoding an attacker can craft a request body that can make the server crash with the following request: "curl -d "array[_0][0][array][_0][0][array]$(for f in $(seq 1100); do echo -n '[_0][0][array]'; done)[string][_0]=hello%20world" http://localhost:8080/foo". The issue is unbounded, attacker controlled stack growth which will at some point lead to a stack overflow and a process crash. This issue has been fixed in version 4.61.1.