MEDIUM
GHSA-89vf-4333-qx8v
Rails Active Support has a possible XSS vulnerability in SafeBuffer#%
Details
### Impact `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.
### Releases The fixed releases are available at the normal locations.
### Credit This issue was responsibly reported by @ch4n3-yoon
Are you affected?
Enter the version of the package you're using.
Affected packages
RubyGems / activesupport
Introduced in:
8.1.0.beta1 Fixed in: 8.1.2.1 Fix
bundle update activesupport RubyGems / activesupport
Introduced in:
8.0.0.beta1 Fixed in: 8.0.4.1 Fix
bundle update activesupport References
- https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v [WEB]
- https://nvd.nist.gov/vuln/detail/CVE-2026-33170 [ADVISORY]
- https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7 [WEB]
- https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db [WEB]
- https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb [WEB]
- https://github.com/rails/rails [PACKAGE]
- https://github.com/rails/rails/releases/tag/v7.2.3.1 [WEB]
- https://github.com/rails/rails/releases/tag/v8.0.4.1 [WEB]
- https://github.com/rails/rails/releases/tag/v8.1.2.1 [WEB]
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activesupport/CVE-2026-33170.yml [WEB]