CVE-2026-33167: Rubyonrails Rails

Medium severity, CVSS 6.1. EPSS: 0.3% chance of exploitation in the next 30 days.

Action Pack is a Rubygem for building web applications on the Rails framework. In versions on the 8.1 branch prior to 8.1.2.1, the debug exceptions page does not properly escape exception messages. A carefully crafted exception message could inject arbitrary HTML and JavaScript into the page, leading to XSS. This affects applications with detailed exception pages enabled (`config.consider_all_requests_local = true`), which is the default in development. Version 8.1.2.1 contains a patch.

Affected products

• Rubyonrails Rails: from 8.1.0, before 8.1.2.1 (fixed in 8.1.2.1)

Published 2026-03-23. Last modified 2026-08-12.