{"id":"DEBIAN-CVE-2026-33916","details":"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.","modified":"2026-09-14T17:03:08.814735900Z","published":"2026-03-27T21:17:27.237Z","upstream":["CVE-2026-33916"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-33916"}],"affected":[{"package":{"name":"node-handlebars","ecosystem":"Debian:12","purl":"pkg:deb/debian/node-handlebars?arch=source&distro=bookworm"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.7.7+~4.1.0-1","3:4.7.9-1","3:4.7.9-2","3:4.7.9-3","3:4.7.9-4","3:4.7.9-5","3:4.7.9-6"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33916.json"}},{"package":{"name":"node-handlebars","ecosystem":"Debian:13","purl":"pkg:deb/debian/node-handlebars?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.7.7+~4.1.0-1","3:4.7.9-1","3:4.7.9-2","3:4.7.9-3","3:4.7.9-4","3:4.7.9-5","3:4.7.9-6"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33916.json"}},{"package":{"name":"node-handlebars","ecosystem":"Debian:14","purl":"pkg:deb/debian/node-handlebars?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"3:4.7.9-1"}]}],"versions":["3:4.7.7+~4.1.0-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33916.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N"}]}