GHSA-89vf-4333-qx8v
Rails Active Support has a possible XSS vulnerability in SafeBuffer#%
Packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| RubyGems | activesupport | >= 8.1.0.beta1, < 8.1.2.1 | 8.1.2.1 |
| RubyGems | activesupport | >= 8.0.0.beta1, < 8.0.4.1 | 8.0.4.1 |
| RubyGems | activesupport | < 7.2.3.1 | 7.2.3.1 |
Details
As written in the advisory (Markdown source, shown as plain text).
### 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
References
External links from the advisory. They lead to third-party sites.
- https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8v
- https://nvd.nist.gov/vuln/detail/CVE-2026-33170
- https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7
- https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2db
- https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035beb
- https://github.com/rails/rails
- https://github.com/rails/rails/releases/tag/v7.2.3.1
- https://github.com/rails/rails/releases/tag/v8.0.4.1
- https://github.com/rails/rails/releases/tag/v8.1.2.1
- https://github.com/rubysec/ruby-advisory-db/blob/master/gems/activesupport/CVE-2026-33170.yml