Allocation of Resources Without Limits or Throttling Affecting rack package, versions <2.2.18

rack is a minimal, modular and adaptable interface for developing web applications in Ruby. By wrapping HTTP requests and responses in the simplest way possible, it unifies and distills the API for web servers, web frameworks, and software in between (the so-called middleware) into a single method call.

Affected versions of this package are vulnerable to Allocation of Resources Without Limits or Throttling due to params_limit only being enforced for parameters separated by &, while still splitting on both & and ; in the QueryParser. An attacker can exhaust system resources and cause service disruption by submitting a large number of parameters separated by semicolons, bypassing the intended parameter count limit.

Note:

This is only exploitable if the QueryParser is used directly with its default configuration (no explicit delimiter).

This vulnerability can be mitigated by configuring QueryParser with an explicit delimiter (such as &) or by enforcing query string and request size limits at the web server or proxy layer to mitigate excessive parsing overhead.

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