{"id":"CVE-2026-33939","revision":"69441d1f6a7b473885abeb857584064c","records":[{"revision":"69441d1f6a7b473885abeb857584064c","observedAt":"2026-10-23T15:48:27.903+00:00","statement":{"source":"cve-program","id":"CVE-2026-33939","aliases":[],"title":"Handlebars.js has Denial of Service via Malformed Decorator Syntax in Template Compilation","description":"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.","state":0,"publishedAt":"2026-03-27T21:08:24.664+00:00","modifiedAt":"2026-09-04T12:04:44.445+00:00","affected":[{"ecosystem":"Vendor product","name":"handlebars.js","ranges":[],"versions":[],"rawVersionEvidence":"{\n                    \"vendor\": \"handlebars-lang\",\n                    \"product\": \"handlebars.js\",\n                    \"versions\": [\n                        {\n                            \"version\": \">= 4.0.0, < 4.7.9\",\n                            \"status\": \"affected\"\n                        }\n                    ]\n                }"}],"metrics":[{"system":"CVSS 3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H","score":7.5,"severity":"HIGH"}],"references":["https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff","https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2","https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9"],"sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-33939","license":"CVE Program Terms of Use","key":"cve-program:CVE-2026-33939","identifiers":["CVE-2026-33939"]},"retained":false,"historicalAffected":[]}],"coverage":[]}