Rails has a possible XSS vulnerability in its Action Pack debug exceptions

Not analysed yet

We haven’t published our analysis of this Advisory yet. Once a person has reviewed it, this page will say what’s vulnerable, what has to be true for your app to be affected, and how to check.

Severity and exploitation

• CISA KEV Not listed.
• EPSS 0.0026, the 17th percentile, on 5 Nov 2026: FIRST’s estimate of the chance of exploitation in the next 30 days.

Timeline

1. 31 Oct 2026, 15:16 UTC First seen by agentprime
2. 31 Oct 2026, 15:16 UTC Confirmed by OSV

Sources

• GitHub Advisory Database: GHSA-pgm4-439c-5jp6
• OSV: GHSA-pgm4-439c-5jp6
• github.com/rails/rails/security/advisories/GHSA-pgm4-439c-5jp6
• nvd.nist.gov/vuln/detail/CVE-2026-33167
• github.com/rails/rails/commit/6752711c8c31d79ba50d13af6a6698a3b85415e0
• github.com/rails/rails
• github.com/rails/rails/releases/tag/v8.1.2.1
• github.com/rubysec/ruby-advisory-db/blob/master/gems/actionpack/CVE-2026-33167.yml

Facts on this page come from the GitHub Advisory Database (CC-BY 4.0), OSV and the other sources listed, as published. We don’t reproduce full advisory descriptions, which can contain exploit code.