XSS in Rails Actionpack
CVE-2026-33167
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.
Vulnerability class: XSS (Cross-Site Scripting)
EPSS: 0.004 (32.8th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 6.1 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N.
Affected products
- Rails Actionpack — versions >= 8.1.0, < 8.1.2.1
- Rubyonrails Rails
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-33167?
- CVE-2026-33167 is a medium-severity vulnerability in Rails Actionpack, classified under Cross-site Scripting. CVSS score: 6.1/10. Published 2026-03-23.
- How severe is CVE-2026-33167?
- Medium severity. CVSS v3 base score is 6.1 out of 10.