{"id":"DEBIAN-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":"2026-09-05T08:47:32.781008519Z","published":"2026-03-27T22:16:21.030Z","upstream":["CVE-2026-33940"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2026-33940"}],"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/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33940.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/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33940.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/osv-test-debian-osv/debian-cve-osv/DEBIAN-CVE-2026-33940.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}