CVE-2026-33167: Rails has a possible XSS vulnerability in its Action Pack debug exceptions

March 23, 2026

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.

References

github.com/advisories/GHSA-pgm4-439c-5jp6
github.com/rails/rails
github.com/rails/rails/commit/6752711c8c31d79ba50d13af6a6698a3b85415e0
github.com/rails/rails/releases/tag/v8.1.2.1
github.com/rails/rails/security/advisories/GHSA-pgm4-439c-5jp6
nvd.nist.gov/vuln/detail/CVE-2026-33167

Code Behaviors & Features

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