---
id: CVE-2026-33167
title: Action Pack is a Rubygem for building web applications on the Rails framework
summary: >-
  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
  c…
severity: medium
cvss: 6.1
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N'
cwe:
  - CWE-79
vendor: rubyonrails
product: rails
affected:
  - 'rails >= 8.1.0, < 8.1.2.1'
patched:
  - rails 8.1.2.1
published: '2026-03-23'
updated: '2026-08-12'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-33167'
references:
  - url: >-
      https://github.com/rails/rails/commit/6752711c8c31d79ba50d13af6a6698a3b85415e0
    label: security-advisories@github.com
  - url: 'https://github.com/rails/rails/releases/tag/v8.1.2.1'
    label: security-advisories@github.com
  - url: 'https://github.com/rails/rails/security/advisories/GHSA-pgm4-439c-5jp6'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.0025
epssPercentile: 0.16729
ingestedAt: '2026-08-12T19:54:26.835Z'
---

## Overview

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

- `rails >= 8.1.0, < 8.1.2.1`

## Remediation

Upgrade past the affected range:

- `rails 8.1.2.1`