Answer in brief
CVE-2026-33170 records a Unknown severity vulnerability in Rails Active Support has a possible XSS vulnerability in SafeBuffer#%. The current sources do not mark it as known exploited. The current feed maps activesupport (rubygems), activesupport (rubygems), activesupport (rubygems). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
A CVSS score is not reported in the current record. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps activesupport (rubygems), activesupport (rubygems), activesupport (rubygems). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| activesupportrubygems | >=8.1.0.beta1 <8.1.2.1 | 8.1.2.1 |
| activesupportrubygems | >=8.0.0.beta1 <8.0.4.1 | 8.0.4.1 |
| activesupportrubygems | >=0 <7.2.3.1 | 7.2.3.1 |
Published upstream
Mar 23, 2026
Evidence: source:osv:source_dates:source-dates:recordSource modified
Sep 10, 2026
Evidence: source:osv:source_dates:source-dates:recordFirst seen by HOL
Aug 7, 2026
### 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
Quoted source text, attributed separately from HOL analysis.