{"id":"UBUNTU-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":"2026-04-27T20:08:47.659131Z","published":"2026-03-27T21:17:00Z","upstream":["CVE-2026-33916"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-33916"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-33916"},{"type":"REPORT","url":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-2qvq-rjwj-gvw9"},{"type":"REPORT","url":"https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2"},{"type":"REPORT","url":"https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2"},{"type":"REPORT","url":"https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9"}],"affected":[{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:18.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars@3:4.0.10-5?arch=source&distro=bionic"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.0.10-5"],"ecosystem_specific":{"binaries":[{"binary_name":"handlebars","binary_version":"3:4.0.10-5"},{"binary_name":"libjs-handlebars","binary_version":"3:4.0.10-5"},{"binary_name":"libjs-handlebars.runtime","binary_version":"3:4.0.10-5"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars@3:4.7.2-1?arch=source&distro=focal"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.1.0-1","3:4.5.3-1","3:4.7.2-1"],"ecosystem_specific":{"binaries":[{"binary_name":"handlebars","binary_version":"3:4.7.2-1"},{"binary_name":"libjs-handlebars","binary_version":"3:4.7.2-1"},{"binary_name":"libjs-handlebars.runtime","binary_version":"3:4.7.2-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source&distro=jammy"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.7.6+~4.1.0-2","3:4.7.7+~4.1.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars.runtime","binary_version":"3:4.7.7+~4.1.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.7.7+~4.1.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars.runtime","binary_version":"3:4.7.7+~4.1.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source&distro=questing"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.7.7+~4.1.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars.runtime","binary_version":"3:4.7.7+~4.1.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:26.04","purl":"pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source&distro=resolute"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.7.7+~4.1.0-1"],"ecosystem_specific":{"binaries":[{"binary_name":"handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars","binary_version":"3:4.7.7+~4.1.0-1"},{"binary_name":"libjs-handlebars.runtime","binary_version":"3:4.7.7+~4.1.0-1"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33916.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:L/I:L/A:N"},{"type":"Ubuntu","score":"medium"}]}