CVE-2026-33170

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.

• CWE-79

• https://github.com/rails/rails/commit/50d732af3b7c8aaf63cbcca0becbc00279b215b7Patch
• https://github.com/rails/rails/commit/6e8a81108001d58043de9e54a06fca58962fc2dbPatch
• https://github.com/rails/rails/commit/c1ad0e8e1972032f3395853a5e99cea035035bebPatch
• https://github.com/rails/rails/releases/tag/v7.2.3.1Release Notes
• https://github.com/rails/rails/releases/tag/v8.0.4.1Release Notes
• https://github.com/rails/rails/releases/tag/v8.1.2.1Release Notes
• https://github.com/rails/rails/security/advisories/GHSA-89vf-4333-qx8vVendor Advisory

Published

Mar 24, 2026

Last Modified

Jun 17, 2026

Status

Analyzed

• How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
• Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
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