A regular expression based DoS vulnerability in Action Dispatch <6.1.7.1 and <7.0.4.1 related to the If-None-Match header. A specially crafted HTTP If-None-Match header can cause the regular expression engine to enter a state of catastrophic backtracking, when on a version of Ruby below 3.2.0. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability All users running an affected release should either upgrade or use one of the workarounds immediately.

A regular expression based DoS vulnerability in Action Dispatch <6.0.6.1,< 6.1.7.1, and <7.0.4.1. Specially crafted cookies, in combination with a specially crafted X_FORWARDED_HOST header can cause the regular expression engine to enter a state of catastrophic backtracking. This can cause the process to use large amounts of CPU and memory, leading to a possible DoS vulnerability All users running an affected release should either upgrade or use one of the workarounds immediately.

Puma is a Ruby/Rack web server built for parallelism. Prior to `puma` version `5.6.2`, `puma` may not always call `close` on the response body. Rails, prior to version `7.0.2.2`, depended on the response body being closed in order for its `CurrentAttributes` implementation to work correctly. The combination of these two behaviors (Puma not closing the body + Rails' Executor implementation) causes information leakage. This problem is fixed in Puma versions 5.6.2 and 4.3.11. This problem is fixed in Rails versions 7.02.2, 6.1.4.6, 6.0.4.6, and 5.2.6.2. Upgrading to a patched Rails _or_ Puma version fixes the vulnerability.

Action Pack is a framework for handling and responding to web requests. Under certain circumstances response bodies will not be closed. In the event a response is *not* notified of a `close`, `ActionDispatch::Executor` will not know to reset thread local state for the next request. This can lead to data being leaked to subsequent requests.This has been fixed in Rails 7.0.2.1, 6.1.4.5, 6.0.4.5, and 5.2.6.1. Upgrading is highly recommended, but to work around this problem a middleware described in GHSA-wh98-p28r-vrc9 can be used.