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CVE-2025-62496

Estado: AnalizadaAlta (7.1)—

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.

The function calculates the necessary number of bits (n_bits) required to store the BigInt using the formula:

$$\text{n\_bits} = (\text{n\_digits} \times 27 + 7) / 8 \quad (\text{for radix 10})$$

Detalles técnicos trazas, registros y código del informe original
  *  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.

  *  The resulting n_bits value becomes unexpectedly small or even negative due to this wrap-around.

  *  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.

  *  The function proceeds to allocate a JSBigInt object using this underestimated n_limbs.

  *  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.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vector CVSS con AV:A, AC:H, UI:P indica explotación cliente que requiere interacción (T1203). El overflow en parsing BigInt permite escritura fuera de límites (heap OOB), facilitando ejecución de código (T1059) o escalada de privilegios (T1068).

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Execution PreventionApplication Isolation and SandboxingExploit ProtectionUpdate SoftwareThreat Intelligence ProgramRestrict Web-Based Content

Tecnologías afectadas (1)

Quickjs Project — Quickjs

CWE

Referencias

JSON original (NVD)

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