ubuntu-cve-2026-33939
Vulnerability from osv_ubuntu
Published
2026-03-27 22:16
Modified
2026-06-30 16:20
Summary
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.

Severity
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
7.5 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
N/A (UNKNOWN)
medium
References
To clipboard 

{
  "affected": [
    {
      "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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:18.04:LTS",
        "name": "node-handlebars",
        "purl": "pkg:deb/ubuntu/node-handlebars@3:4.0.10-5?arch=source\u0026distro=bionic"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3:4.0.10-5"
      ]
    },
    {
      "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_name": "libjs-handlebars.runtime",
            "binary_version": "3:4.7.2-1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:20.04:LTS",
        "name": "node-handlebars",
        "purl": "pkg:deb/ubuntu/node-handlebars@3:4.7.2-1?arch=source\u0026distro=focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3:4.1.0-1",
        "3:4.5.3-1",
        "3:4.7.2-1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "handlebars",
            "binary_version": "3:4.7.7+~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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "node-handlebars",
        "purl": "pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3:4.7.6+~4.1.0-2",
        "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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "node-handlebars",
        "purl": "pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source\u0026distro=noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:25.10",
        "name": "node-handlebars",
        "purl": "pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source\u0026distro=questing"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "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"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "node-handlebars",
        "purl": "pkg:deb/ubuntu/node-handlebars@3:4.7.7+~4.1.0-1?arch=source\u0026distro=resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "3:4.7.7+~4.1.0-1"
      ]
    }
  ],
  "aliases": [],
  "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": "UBUNTU-CVE-2026-33939",
  "modified": "2026-06-30T16:20:55Z",
  "published": "2026-03-27T22:16:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-33939"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-33939"
    },
    {
      "type": "REPORT",
      "url": "https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-9cx6-37pm-9jff"
    },
    {
      "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"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-33939"
  ]
}



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