{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "versions": [
              {
                "introduced": "4.0.0"
              },
              {
                "fixed": "4.7.9"
              }
            ]
          },
          "events": [
            {
              "introduced": "bff5fab8f9d42e21950be00dcf1cedf4dc1a565b"
            },
            {
              "fixed": "dce542c9a660048d31f0981ac8a45c08b919bddb"
            }
          ],
          "repo": "https://github.com/handlebars-lang/handlebars.js",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-9cx6-37pm-9jff"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-754"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33939.json"
  },
  "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.",
  "id": "CVE-2026-33939",
  "modified": "2026-04-01T23:09:02.724998483Z",
  "published": "2026-03-27T21:08:24.664Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33939.json"
    },
    {
      "type": "FIX",
      "url": "https://github.com/handlebars-lang/handlebars.js/commit/68d8df5a88e0a26fe9e6084c5c6aaebe67b07da2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.9"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33939"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Handlebars.js has Denial of Service via Malformed Decorator Syntax in Template Compilation"
}