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TI-2026-25600 Aliases CVE-2026-33170GHSA-89vf-4333-qx8v

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

Priority LOW 24CWE-79Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Passive
Attack complexity
Low
Attack requirements
None
Impact type
Cross-site scripting
Confidentiality · integrity · availability
None · Low · None
Fix status
Partial Red Hat: 1 without a fix

Attack profile from CVSS 4.0 · CNA. Fix status from CNA, GitHub and Red Hat. Impact type from CWE-79.

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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.0034 27th percentileScored 2026-11-07
Fix Partial activesupport (rails): 8.1.2.1, 8.0.4.1, 7.2.3.1activesupport (RubyGems): 8.1.2.1, 8.0.4.1, 7.2.3.1Red Hat: 1 without a fix

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
Railsactivesupport8.1.0.beta1 to before 8.1.2.1; 8.0.0.beta1 to before 8.0.4.1; before 7.2.3.18.1.2.1, 8.0.4.1, 7.2.3.1Patch availableCNA
—activesupport (RubyGems)8.1.0.beta1 to before 8.1.2.18.1.2.1Patch availableGHSA-89vf-4333-qx8v
—activesupport (RubyGems)8.0.0.beta1 to before 8.0.4.18.0.4.1Patch availableGHSA-89vf-4333-qx8v
—activesupport (RubyGems)before 7.2.3.17.2.3.1Patch availableGHSA-89vf-4333-qx8v
  • activesupport VendorRails Affected 8.1.0.beta1 to before 8.1.2.1; 8.0.0.beta1 to before 8.0.4.1; before 7.2.3.1 Fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1 Patch available CNA
  • activesupport (RubyGems) Vendor— Affected 8.1.0.beta1 to before 8.1.2.1 Fixed in 8.1.2.1 Patch available GHSA-89vf-4333-qx8v
  • activesupport (RubyGems) Vendor— Affected 8.0.0.beta1 to before 8.0.4.1 Fixed in 8.0.4.1 Patch available GHSA-89vf-4333-qx8v
  • activesupport (RubyGems) Vendor— Affected before 7.2.3.1 Fixed in 7.2.3.1 Patch available GHSA-89vf-4333-qx8v

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:*before 7.2.3.1; 8.0.0 to before 8.0.4.1; 8.1.0 to before 8.1.2.1VulnerableRails
  • cpe:2.3:a:rubyonrails:rails:*:*:*:*:*:*:*:* Versions before 7.2.3.1; 8.0.0 to before 8.0.4.1; 8.1.0 to before 8.1.2.1 Vulnerable ·Rails

Remediation

  • Fix · CNA activesupport (rails) Fixed in 8.1.2.1, 8.0.4.1, 7.2.3.1
  • Fix · GHSA-89vf-4333-qx8v activesupport (RubyGems) Fixed in 8.1.2.1 Advisory →
  • Fix · GHSA-89vf-4333-qx8v activesupport (RubyGems) Fixed in 8.0.4.1 Advisory →
  • Fix · GHSA-89vf-4333-qx8v activesupport (RubyGems) Fixed in 7.2.3.1 Advisory →

Vendor assessments

Red Hat

Red Hat rating: Moderate. Red Hat's page for this CVE →

ProductStatusPlan or fix
Red Hat Satellite 6AffectedNo fix yet: Fix deferred

Timeline

  1. 2026-10-02 Threatist record created from CVE-2026-33170
  2. 2026-10-03 Alias added: GHSA-89vf-4333-qx8v

References

Patch 3

Advisory 2

Other 5

  • TI-2014-00124 Directory traversal vulnerability in actionpack/lib/abstract_controller/base.rb in the… KEVCVSS 3.1HIGH 7.5
  • TI-2019-03828 Path traversal in Rails https://github.com/rails/rails KEVCVSS 3.1HIGH 7.5
  • TI-2016-00672 Directory traversal vulnerability in Action View in Ruby on Rails before 3.2.22.1, 4.0.x… KEVCVSS 3.1HIGH 7.5
  • TI-2019-03830 Command injection in Rails https://github.com/rails/rails CVSS 3.1CRITICAL 9.8
  • TI-2020-06581 Code injection in https://github.com/rails/rails CVSS 3.1HIGH 8.8
  • TI-2013-00091 active_support/core_ext/hash/conversions.rb in Ruby on Rails before 2.3.15, 3.0.x before… CVSS 2.0HIGH 7.5
See all 117 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences