{"id":"UBUNTU-CVE-2026-33939","details":"Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, when a Handlebars template contains decorator syntax referencing an unregistered decorator (e.g. `{{*n}}`), the compiled template calls `lookupProperty(decorators, \"n\")`, which returns `undefined`. The runtime then immediately invokes the result as a function, causing an unhandled `TypeError: ... is not a function` that crashes the Node.js process. Any application that compiles user-supplied templates without wrapping the call in a `try/catch` is vulnerable to a single-request Denial of Service. Version 4.7.9 fixes the issue. Some workarounds are available. Wrap compilation and rendering in `try/catch`. Validate template input before passing it to `compile()`; reject templates containing  decorator syntax (`{{*...}}`) if decorators are not used in your application. Use the pre-compilation workflow; compile templates at build time and serve only pre-compiled  templates; do not call `compile()` at request time.","modified":"2026-06-30T18:17:56.833240609Z","published":"2026-03-27T22:16:00Z","upstream":["CVE-2026-33939"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-33939"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-33939"},{"type":"REPORT","url":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff"},{"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?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_version":"3:4.0.10-5","binary_name":"libjs-handlebars.runtime"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33939.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:20.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars?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_version":"3:4.7.2-1","binary_name":"libjs-handlebars"},{"binary_version":"3:4.7.2-1","binary_name":"libjs-handlebars.runtime"}]},"database_specific":{"source":"https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2026/UBUNTU-CVE-2026-33939.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:22.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars?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_version":"3:4.7.7+~4.1.0-1","binary_name":"handlebars"},{"binary_version":"3:4.7.7+~4.1.0-1","binary_name":"libjs-handlebars"},{"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-2026-33939.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:24.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars?arch=source&distro=noble"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["3:4.7.7+~4.1.0-1"],"ecosystem_specific":{"binaries":[{"binary_version":"3:4.7.7+~4.1.0-1","binary_name":"handlebars"},{"binary_version":"3:4.7.7+~4.1.0-1","binary_name":"libjs-handlebars"},{"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-2026-33939.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:25.10","purl":"pkg:deb/ubuntu/node-handlebars?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-2026-33939.json"}},{"package":{"name":"node-handlebars","ecosystem":"Ubuntu:26.04:LTS","purl":"pkg:deb/ubuntu/node-handlebars?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_version":"3:4.7.7+~4.1.0-1","binary_name":"libjs-handlebars"},{"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-2026-33939.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"},{"type":"Ubuntu","score":"medium"}]}