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.

An open redirect vulnerability is fixed in Rails 7.0.4.1 with the new protection against open redirects from calling redirect_to with untrusted user input. In prior versions the developer was fully responsible for only providing trusted input. However the check introduced could allow an attacker to bypass with a carefully crafted URL resulting in an open redirect vulnerability.