Answer in brief
CVE-2026-33228 records a High severity (CVSS 8.9) vulnerability in flatted: Prototype Pollution via parse(). The current sources do not mark it as known exploited. The current feed maps Red Hat/3scale-amp20/system (generic), Red Hat/3scale-amp21/system (generic), Red Hat/3scale-amp22/system (generic), Red Hat/3scale-amp24/system (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 8.9. 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 Red Hat/3scale-amp20/system (generic), Red Hat/3scale-amp21/system (generic), Red Hat/3scale-amp22/system (generic), Red Hat/3scale-amp24/system (generic) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Product | Affected versions | Fixed versions |
|---|---|---|
| cpe:2.3:a:webreflection:flatted:*:*:*:*:*:node.js:*:* | Not reported | Not reported |
| Package | Affected range | Fixed version |
|---|---|---|
| Red Hat/3scale-amp20/systemgeneric | * | Not reported |
| Red Hat/3scale-amp21/systemgeneric | * | Not reported |
| Red Hat/3scale-amp22/systemgeneric | * | Not reported |
| Red Hat/3scale-amp24/systemgeneric | * | Not reported |
| Red Hat/3scale-amp25/systemgeneric | * | Not reported |
| Red Hat/3scale-amp26/systemgeneric | * | Not reported |
| Red Hat/3scale-amp2/system-rhel7generic | * | Not reported |
| Red Hat/3scale-amp2/system-rhel8generic | * | Not reported |
| Red Hat/3scale-amp2/system-rhel9generic | * | Not reported |
| WebReflection/flattedgeneric | <3.4.2 | 3.4.2 |
| Red Hat/org.keycloak-keycloak-parentgeneric | * | Not reported |
| Red Hat/rhbk-quarkus-dist.zipgeneric | * | Not reported |
| flattednpm | <=3.4.1 | 3.4.2 |
Published upstream
Mar 20, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Oct 5, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 2, 2026
flatted is a circular JSON parser. Prior to version 3.4.2, the parse() function in flatted can use attacker-controlled string values from the parsed JSON as direct array index keys, without validating that they are numeric. Since the internal input buffer is a JavaScript Array, accessing it with the key "__proto__" returns Array.prototype via the inherited getter. This object is then treated as a legitimate parsed value and assigned as a property of the output object, effectively leaking a live reference to Array.prototype to the consumer. Any code that subsequently writes to that property will pollute the global prototype. This issue has been patched in version 3.4.2.
Quoted source text, attributed separately from HOL analysis.