cvedb.io
CVE-2026-33916
MEDIUM · CVSS 4.7
EPSS exploitation probability: 0%
Published 2026-03-27T21:17:27.237 · Last modified 2026-06-17T10:38:18.863

Summary

Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, `resolvePartial()` in the Handlebars runtime resolves partial names via a plain property lookup on `options.partials` without guarding against prototype-chain traversal. When `Object.prototype` has been polluted with a string value whose key matches a partial reference in a template, the polluted string is used as the partial body and rendered without HTML escaping, resulting in reflected or stored XSS. Version 4.7.9 fixes the issue. Some workarounds are available. Apply `Object.freeze(Object.prototype)` early in application startup to prevent prototype pollution. Note: this may break other libraries, and/or use the Handlebars runtime-only build (`handlebars/runtime`), which doe

Affected products

handlebarsjs — handlebars

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References

This product uses data from the NVD API but is not endorsed or certified by the NVD. Informational only; not professional security advice.