CVE-2026-33170: Rails Active Support has a possible XSS vulnerability in SafeBuffer#%
(updated )
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.
References
- github.com/advisories/GHSA-89vf-4333-qx8v
- github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7
- github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db
- github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb
- github.com/rails/rails/releases/tag/v7.2.3.1
- github.com/rails/rails/releases/tag/v8.0.4.1
- github.com/rails/rails/releases/tag/v8.1.2.1
- github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v
- github.com/rubysec/ruby-advisory-db/blob/master/gems/activesupport/CVE-2026-33170.yml
- nvd.nist.gov/vuln/detail/CVE-2026-33170
Code Behaviors & Features
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