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CVE-2026-33170GHSA-89VF-4333-QX8V

Rails Active Support has a possible XSS vulnerability in SafeBuffer#%

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1
None on Exploit-DB, Metasploit or GitHub
  • Exploitation: none
  • Automatable: no
  • Technical impact: partial

Summary

Active Support is a toolkit of support libraries and Ruby core extensions extracted from the Rails framework. Prior to versions 8.1.2.1, 8.0.4.1, and 7.2.3.1, `SafeBuffer#%` does not propagate the `@html_unsafe` flag to the newly created buffer. If a `SafeBuffer` is mutated in place (e.g. via `gsub!`) and then formatted with `%` using untrusted arguments, the result incorrectly reports `html_safe? == true`, bypassing ERB auto-escaping and possibly leading to XSS. Versions 8.1.2.1, 8.0.4.1, and 7.2.3.1 contain a patch.

Timeline

  1. CVE published
  2. CISA SSVC assessment

    Exploitation: none · Automatable: no · Technical impact: partial

  3. Record last updated

Affected versions

  • rails activesupport

    From 8.1.0.beta1 · fixed in 8.1.2.1; From 8.0.0.beta1 · fixed in 8.0.4.1; fixed in 7.2.3.1

  • activesupportRubyGems

    From 8.1.0.beta1 · fixed in 8.1.2.1

  • activesupportRubyGems

    From 8.0.0.beta1 · fixed in 8.0.4.1

  • activesupportRubyGems

    fixed in 7.2.3.1

References 7

GitHub · rails/rails