{
  "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-3mfm-83xf-c92r"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-843",
      "CWE-94"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33938.json"
  },
  "details": "Handlebars provides the power necessary to let users build semantic templates. In versions 4.0.0 through 4.7.8, the `@partial-block` special variable is stored in the template data context and is reachable and mutable from within a template via helpers that accept arbitrary objects. When a helper overwrites `@partial-block` with a crafted Handlebars AST, a subsequent invocation of `{{\u003e @partial-block}}` compiles and executes that AST, enabling arbitrary JavaScript execution on the server. Version 4.7.9 fixes the issue. Some workarounds are available. First, use the runtime-only build (`require('handlebars/runtime')`). The `compile()` method is  absent, eliminating the vulnerable fallback path. Second, audit registered helpers for any that write arbitrary values to context objects. Helpers  should treat context data as read-only. Third, avoid registering helpers from third-party packages (such as `handlebars-helpers`) in  contexts where templates or context data can be influenced by untrusted input.",
  "id": "CVE-2026-33938",
  "modified": "2026-04-01T23:10:34.880373507Z",
  "published": "2026-03-27T21:05:42.485Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33938.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-3mfm-83xf-c92r"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33938"
    }
  ],
  "schema_version": "1.7.3",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Handlebars.js has JavaScript Injection via AST Type Confusion by tampering @partial-block"
}