{"id":"UBUNTU-CVE-2026-33940","details":"Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, a crafted object placed in the template context can bypass all conditional guards in `resolvePartial()` and cause `invokePartial()` to return `undefined`. The Handlebars runtime then treats the unresolved partial as a source that needs to be compiled, passing the crafted object to `env.compile()`. Because the object is a valid Handlebars AST containing injected code, the generated JavaScript executes arbitrary commands on the server. The attack requires the adversary to control a value that can be returned by a dynamic partial lookup. Version 4.7.9 fixes the issue. Some workarounds are available. First, use the runtime-only build (`require('handlebars/runtime')`). Without `compile()`,  the fallback compilation path in `invokePartial` is unreachable. Second, sanitize context data before rendering: Ensure no value in the context is a non-primitive  object that could be passed to a dynamic partial. Third, avoid dynamic partial lookups (`{{\u003e (lookup ...)}}`) when context data is user-controlled.","modified":"2026-06-30T18:17:56.859347200Z","published":"2026-03-27T22:16:00Z","upstream":["CVE-2026-33940"],"references":[{"type":"REPORT","url":"https://ubuntu.com/security/CVE-2026-33940"},{"type":"REPORT","url":"https://www.cve.org/CVERecord?id=CVE-2026-33940"},{"type":"REPORT","url":"https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-xhpv-hc6g-r9c6"},{"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_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-2026-33940.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_name":"libjs-handlebars","binary_version":"3:4.7.2-1"},{"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-2026-33940.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_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-2026-33940.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_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-2026-33940.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_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-2026-33940.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_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-2026-33940.json"}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"},{"type":"Ubuntu","score":"medium"}]}