CVE-2025-62496

{
  "id": "CVE-2025-62496",
  "sourceIdentifier": "[email protected]",
  "published": "2025-10-16T16:15:40.260",
  "lastModified": "2026-10-19T17:10:00.173",
  "vulnStatus": "Analyzed",
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "A vulnerability exists in the QuickJS engine's BigInt string parsing logic (js_bigint_from_string) when attempting to create a BigInt from a string with an excessively large number of digits.\n\nThe function calculates the necessary number of bits (n_bits) required to store the BigInt using the formula:\n\n$$\\text{n\\_bits} = (\\text{n\\_digits} \\times 27 + 7) / 8 \\quad (\\text{for radix 10})$$\n\n  *  For large input strings (e.g., $79,536,432$ digits or more for base 10), the intermediate calculation $(\\text{n\\_digits} \\times 27 + 7)$ exceeds the maximum value of a standard signed 32-bit integer, resulting in an Integer Overflow.\n\n\n  *  The resulting n_bits value becomes unexpectedly small or even negative due to this wrap-around.\n\n\n  *  This flawed n_bits is then used to compute n_limbs, the number of memory \"limbs\" needed for the BigInt object. Since n_bits is too small, the calculated n_limbs is also significantly underestimated.\n\n\n  *  The function proceeds to allocate a JSBigInt object using this underestimated n_limbs.\n\n\n  *  When the function later attempts to write the actual BigInt data into the allocated object, the small buffer size is quickly exceeded, leading to a Heap Out-of-Bounds Write as data is written past the end of the allocated r->tab array."
    },
    {
      "lang": "es",
      "value": "Una vulnerabilidad existe en la lógica de análisis de cadenas BigInt del motor QuickJS (js_bigint_from_string) al intentar crear un BigInt a partir de una cadena con un número excesivamente grande de dígitos.\n\nLa función calcula el número necesario de bits (n_bits) requerido para almacenar el BigInt utilizando la fórmula:\n\n$$\\text{n\\_bits} = (\\text{n\\_digits} \\times 27 + 7) / 8 \\quad (\\text{para base 10})$$\n\n  *  Para cadenas de entrada grandes (por ejemplo, $79,536,432$ dígitos o más para base 10), el cálculo intermedio $(\\text{n\\_digits} \\times 27 + 7)$ excede el valor máximo de un entero con signo estándar de 32 bits, lo que resulta en un desbordamiento de entero.\n\n\n  *  El valor resultante de n_bits se vuelve inesperadamente pequeño o incluso negativo debido a este ajuste cíclico.\n\n\n  *  Este n_bits defectuoso se utiliza entonces para calcular n_limbs, el número de 'limbs' de memoria necesarios para el objeto BigInt. Dado que n_bits es demasiado pequeño, el n_limbs calculado también se subestima significativamente.\n\n\n  *  La función procede a asignar un objeto JSBigInt utilizando este n_limbs subestimado.\n\n\n  *  Cuando la función intenta posteriormente escribir los datos reales del BigInt en el objeto asignado, el pequeño tamaño del búfer se excede rápidamente, lo que lleva a una escritura fuera de límites en el heap a medida que los datos se escriben más allá del final del array r -> tab asignado."
    }
  ],
  "affected": [
    {
      "source": "[email protected]",
      "affectedData": [
        {
          "vendor": "QuickJS",
          "product": "QuickJS",
          "defaultStatus": "unaffected",
          "collectionURL": "https://bellard.org/quickjs/",
          "packageName": "js_bigint_from_string",
          "versions": [
            {
              "version": "2025-04-26",
              "lessThan": "2025-09-13",
              "versionType": "date",
              "status": "affected"
            }
          ]
        }
      ]
    }
  ],
  "metrics": {
    "cvssMetricV40": [
      {
        "source": "[email protected]",
        "type": "Secondary",
        "cvssData": {
          "version": "4.0",
          "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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "attackVector": "ADJACENT",
          "attackComplexity": "HIGH",
          "attackRequirements": "PRESENT",
          "privilegesRequired": "LOW",
          "userInteraction": "PASSIVE",
          "vulnConfidentialityImpact": "HIGH",
          "vulnIntegrityImpact": "HIGH",
          "vulnAvailabilityImpact": "LOW",
          "subConfidentialityImpact": "HIGH",
          "subIntegrityImpact": "HIGH",
          "subAvailabilityImpact": "LOW",
          "exploitMaturity": "NOT_DEFINED",
          "confidentialityRequirement": "NOT_DEFINED",
          "integrityRequirement": "NOT_DEFINED",
          "availabilityRequirement": "NOT_DEFINED",
          "modifiedAttackVector": "NOT_DEFINED",
          "modifiedAttackComplexity": "NOT_DEFINED",
          "modifiedAttackRequirements": "NOT_DEFINED",
          "modifiedPrivilegesRequired": "NOT_DEFINED",
          "modifiedUserInteraction": "NOT_DEFINED",
          "modifiedVulnConfidentialityImpact": "NOT_DEFINED",
          "modifiedVulnIntegrityImpact": "NOT_DEFINED",
          "modifiedVulnAvailabilityImpact": "NOT_DEFINED",
          "modifiedSubConfidentialityImpact": "NOT_DEFINED",
          "modifiedSubIntegrityImpact": "NOT_DEFINED",
          "modifiedSubAvailabilityImpact": "NOT_DEFINED",
          "Safety": "NOT_DEFINED",
          "Automatable": "NOT_DEFINED",
          "Recovery": "NOT_DEFINED",
          "valueDensity": "NOT_DEFINED",
          "vulnerabilityResponseEffort": "NOT_DEFINED",
          "providerUrgency": "NOT_DEFINED"
        }
      }
    ],
    "cvssMetricV31": [
      {
        "source": "[email protected]",
        "type": "Primary",
        "cvssData": {
          "version": "3.1",
          "vectorString": "CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H",
          "baseScore": 8.8,
          "baseSeverity": "HIGH",
          "attackVector": "ADJACENT_NETWORK",
          "attackComplexity": "LOW",
          "privilegesRequired": "NONE",
          "userInteraction": "NONE",
          "scope": "UNCHANGED",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "availabilityImpact": "HIGH"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 5.9
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "timestamp": "2025-10-16T17:26:14.998141Z",
          "id": "CVE-2025-62496",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "version": "2.0.3"
        }
      }
    ]
  },
  "weaknesses": [
    {
      "source": "[email protected]",
      "type": "Secondary",
      "description": [
        {
          "lang": "en",
          "value": "CWE-190"
        }
      ]
    }
  ],
  "configurations": [
    {
      "nodes": [
        {
          "operator": "OR",
          "negate": false,
          "cpeMatch": [
            {
              "vulnerable": true,
              "criteria": "cpe:2.3:a:quickjs_project:quickjs:*:*:*:*:*:*:*:*",
              "versionEndExcluding": "2025-09-13",
              "matchCriteriaId": "AB84E2DC-74EA-4956-9521-C2B652B8E8C2"
            }
          ]
        }
      ]
    }
  ],
  "references": [
    {
      "url": "https://bellard.org/quickjs/Changelog",
      "source": "[email protected]",
      "tags": [
        "Release Notes"
      ]
    },
    {
      "url": "https://issuetracker.google.com/434193016",
      "source": "[email protected]",
      "tags": [
        "Exploit",
        "Issue Tracking"
      ]
    }
  ]
}