CVE-2026-33170
Medium
Description
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.
SeverityMedium
CVSS6.1
Exploit probability—
ProductRails
PublishedMar 24, 2026
First seenMar 24, 2026
Weakness typeCWE-79Cross-site scripting (XSS)
How to fix
Update
- rubyonrails rails7.2.3.1, 8.0.4.1, 8.1.2.1 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| rubyonrails rails | v < 7.2.3.1, 8.0.0 ≤ v < 8.0.4.1, 8.1.0 ≤ v < 8.1.2.1 | 7.2.3.1, 8.0.4.1, 8.1.2.1 |
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