{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2025-62494",
                "options": [
                  {
                    "Exploitation": "poc"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "total"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2025-10-16T17:46:18.542287Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2025-10-16T17:46:39.174Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "collectionURL": "https://bellard.org/quickjs/",
          "defaultStatus": "unaffected",
          "packageName": "JS_ConcatStringInPlace",
          "product": "QuickJS",
          "vendor": "QuickJS",
          "versions": [
            {
              "lessThan": "2025-09-13",
              "status": "affected",
              "version": "2025-04-26",
              "versionType": "date"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Google Big Sleep"
        }
      ],
      "datePublic": "2025-07-24T22:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "supportingMedia": [
            {
              "base64": false,
              "type": "text/html",
              "value": "\u003cp\u003eA type confusion vulnerability exists in the handling of the \u003cb\u003estring addition (\u003ccode\u003e+\u003c/code\u003e) operation\u003c/b\u003e within the QuickJS engine.\u003c/p\u003e\u003col\u003e\u003cli\u003e\u003cp\u003eThe code first checks if the \u003cb\u003eleft-hand operand\u003c/b\u003e is a \u003cb\u003estring\u003c/b\u003e.\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eIt then attempts to convert the \u003cb\u003eright-hand operand\u003c/b\u003e to a primitive value using \u003ccode\u003eJS_ToPrimitiveFree\u003c/code\u003e. This conversion can trigger a \u003cb\u003ecallback\u003c/b\u003e (e.g., \u003ccode\u003etoString\u003c/code\u003e or \u003ccode\u003evalueOf\u003c/code\u003e).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eDuring this callback, an attacker can modify the \u003cb\u003etype\u003c/b\u003e of the \u003cb\u003eleft-hand operand\u003c/b\u003e in memory, changing it from a string to a different type (e.g., an object or an array).\u003c/p\u003e\u003c/li\u003e\u003cli\u003e\u003cp\u003eThe code then proceeds to call \u003ccode\u003eJS_ConcatStringInPlace\u003c/code\u003e, which still treats the modified left-hand value as a string.\u003c/p\u003e\u003c/li\u003e\u003c/ol\u003e\u003cp\u003eThis mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a \u003cb\u003etype confusion condition\u003c/b\u003e. This can lead to out-of-bounds memory access, potentially resulting in \u003cb\u003ememory corruption\u003c/b\u003e and \u003cb\u003earbitrary code execution\u003c/b\u003e in the context of the QuickJS runtime.\u003c/p\u003e\u003cbr\u003e"
            }
          ],
          "value": "A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine.\n\n  *  The code first checks if the left-hand operand is a string.\n\n\n  *  It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf).\n\n\n  *  During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array).\n\n\n  *  The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string.\n\n\nThis mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-175",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-175 Code Inclusion"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
            "Automatable": "NOT_DEFINED",
            "Recovery": "NOT_DEFINED",
            "Safety": "NOT_DEFINED",
            "attackComplexity": "HIGH",
            "attackRequirements": "PRESENT",
            "attackVector": "ADJACENT",
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "privilegesRequired": "LOW",
            "providerUrgency": "NOT_DEFINED",
            "subAvailabilityImpact": "LOW",
            "subConfidentialityImpact": "HIGH",
            "subIntegrityImpact": "HIGH",
            "userInteraction": "PASSIVE",
            "valueDensity": "NOT_DEFINED",
            "vectorString": "CVSS:4.0/AV:A/AC:H/AT:P/PR:L/UI:P/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L",
            "version": "4.0",
            "vulnAvailabilityImpact": "LOW",
            "vulnConfidentialityImpact": "HIGH",
            "vulnIntegrityImpact": "HIGH",
            "vulnerabilityResponseEffort": "NOT_DEFINED"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-704",
              "description": "CWE-704 Incorrect Type Conversion or Cast",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2025-10-16T15:51:50.977Z",
        "orgId": "14ed7db2-1595-443d-9d34-6215bf890778",
        "shortName": "Google"
      },
      "references": [
        {
          "url": "https://bellard.org/quickjs/Changelog"
        },
        {
          "url": "https://issuetracker.google.com/434193023"
        }
      ],
      "source": {
        "discovery": "UNKNOWN"
      },
      "title": "Type confusion in string addition in QuickJS",
      "x_generator": {
        "engine": "Vulnogram 0.2.0"
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    }
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  "cveMetadata": {
    "assignerOrgId": "14ed7db2-1595-443d-9d34-6215bf890778",
    "assignerShortName": "Google",
    "cveId": "CVE-2025-62494",
    "datePublished": "2025-10-16T15:51:50.977Z",
    "dateReserved": "2025-10-15T08:47:41.878Z",
    "dateUpdated": "2025-10-16T17:46:39.174Z",
    "state": "PUBLISHED"
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  "dataType": "CVE_RECORD",
  "dataVersion": "5.1"
}