CVE-2026-106445 (GCVE-0-2026-106445)

Vulnerability from cvelistv5 – Published: 2026-10-06 19:39 – Updated: 2026-10-06 19:39
VLAI
Title
Handlebars: JavaScript Injection via Own Property Check Bypass
Summary
Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars lookupProperty returns Function.prototype.constructor before applying the prototype-access deny list because constructor is an own property of Function.prototype. When an attacker can render a controlled template with allowProtoMethodsByDefault enabled and an accessible function in the template context, the template can traverse from that function through its prototype to Function.prototype and then obtain the Function constructor through the own-property bypass. This permits attacker-controlled JavaScript to execute with the server application's privileges. This issue is fixed in version 4.7.10.
Severity
9.2 (Critical)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
CWE
  • CWE-184 - Incomplete List of Disallowed Inputs
  • CWE-1289 - Improper Validation of Unsafe Equivalence in Input
Assigner
References
Impacted products
Vendor Product Version CPE status
handlebars-lang handlebars.js Affected: >= 4.0.0, < 4.7.10
guessed Create a notification for this product.
Show details on NVD website
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        }
      ],
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            "privilegesRequired": "NONE",
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            "subConfidentialityImpact": "NONE",
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              "description": "CWE-184: Incomplete List of Disallowed Inputs",
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              "type": "CWE"
            }
          ]
        },
        {
          "descriptions": [
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              "cweId": "CWE-1289",
              "description": "CWE-1289: Improper Validation of Unsafe Equivalence in Input",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
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          "name": "https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-p8wg-vrv2-v86f",
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          "url": "https://github.com/handlebars-lang/handlebars.js/security/advisories/GHSA-p8wg-vrv2-v86f"
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          "url": "https://github.com/handlebars-lang/handlebars.js/pull/2185"
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          "url": "https://github.com/handlebars-lang/handlebars.js/commit/ceec388abe1d1aac8f6369860d5f390fa71ef4fa"
        },
        {
          "name": "https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10",
          "tags": [
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          "url": "https://github.com/handlebars-lang/handlebars.js/releases/tag/v4.7.10"
        }
      ],
      "source": {
        "advisory": "GHSA-p8wg-vrv2-v86f",
        "discovery": "UNKNOWN"
      },
      "title": "Handlebars: JavaScript Injection via Own Property Check Bypass"
    }
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    "cveId": "CVE-2026-106445",
    "datePublished": "2026-10-06T19:39:08.916Z",
    "dateReserved": "2026-10-06T16:49:40.590Z",
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    "state": "PUBLISHED"
  },
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      "percentile": "0.33314"
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    "nvd": {
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                "product": "handlebars.js",
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                    "status": "affected",
                    "version": "\u003e= 4.0.0, \u003c 4.7.10"
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        "descriptions": [
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            "lang": "en",
            "value": "Handlebars provides the power necessary to let users build semantic templates. From 4.0.0 until 4.7.10, Handlebars lookupProperty returns Function.prototype.constructor before applying the prototype-access deny list because constructor is an own property of Function.prototype. When an attacker can render a controlled template with allowProtoMethodsByDefault enabled and an accessible function in the template context, the template can traverse from that function through its prototype to Function.prototype and then obtain the Function constructor through the own-property bypass. This permits attacker-controlled JavaScript to execute with the server application\u0027s privileges. This issue is fixed in version 4.7.10."
          }
        ],
        "id": "CVE-2026-106445",
        "lastModified": "2026-10-07T13:58:29.527",
        "metrics": {
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                "Recovery": "NOT_DEFINED",
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                "exploitMaturity": "NOT_DEFINED",
                "integrityRequirement": "NOT_DEFINED",
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                "modifiedAttackRequirements": "NOT_DEFINED",
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                "modifiedPrivilegesRequired": "NOT_DEFINED",
                "modifiedSubAvailabilityImpact": "NOT_DEFINED",
                "modifiedSubConfidentialityImpact": "NOT_DEFINED",
                "modifiedSubIntegrityImpact": "NOT_DEFINED",
                "modifiedUserInteraction": "NOT_DEFINED",
                "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
                "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
                "modifiedVulnIntegrityImpact": "NOT_DEFINED",
                "privilegesRequired": "NONE",
                "providerUrgency": "NOT_DEFINED",
                "subAvailabilityImpact": "NONE",
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                "valueDensity": "NOT_DEFINED",
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                "vulnerabilityResponseEffort": "NOT_DEFINED"
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            "source": "security-advisories@github.com",
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    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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Nomenclature

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



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