There is a possible regular expression based DoS vulnerability in Action
Dispatch. This vulnerability has been assigned the CVE identifier
CVE-2023-22792.

Versions Affected: >= 3.0.0
Not affected: < 3.0.0
Fixed Versions: 5.2.8.15 (Rails LTS), 6.1.7.1, 7.0.4.1

Impact

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.

Workarounds

We recommend that all users upgrade to one of the FIXED versions. In the
meantime, users can mitigate this vulnerability by using a load balancer or
other device to filter out malicious X_FORWARDED_HOST headers before they
reach the application.