Report: - Handlebars.js has Prototype Pollution Leading to XSS through Partial Template In... CVE-2026-33916

Report: - Handlebars.js has Prototype Pollution Leading to XSS through Partial Template In... CVE-2026-33916

CVE ID :CVE-2026-33916 Published : March 27, 2026, 9:17 p.m. | 35 minutes ago Description :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 does not compile templates and reduces the attack surface. Severity: 4.7 | MEDIUM Visit the link for more details, such as CVSS details, affected products, timeline, and more...

CVE Details

Severity
MEDIUM
Published
March 27, 2026
Impact: XSS