{"id":"CVE-2025-62496","state":"PUBLISHED","title":"Integer overflow in js_bigint_from_string in QuickJS","description":"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.","publishedAt":"2025-10-16T15:52:05.654Z","updatedAt":"2025-10-16T17:26:25.654Z","severity":{"score":7.1,"label":"High","version":"4.0","vector":"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","source":"Google"},"assigner":"Google","products":["QuickJS QuickJS"],"affected":[{"vendor":"QuickJS","product":"QuickJS","packageName":"js_bigint_from_string","defaultStatus":"unaffected","versions":[{"version":"2025-04-26","status":"affected","lessThan":"2025-09-13","versionType":"date"}],"collectionURL":"https://bellard.org/quickjs/"}],"references":["https://bellard.org/quickjs/Changelog","https://issuetracker.google.com/434193016"],"weaknesses":["CWE-190"],"ingestedAt":"2026-10-29T20:09:48.677Z","source":{"repository":"CVEProject/cvelistV5","path":"cves/2025/62xxx/CVE-2025-62496.json","commit":"556c9d3a8cd17e218bb8e452ba7cd619a384ff47"},"raw":{"dataType":"CVE_RECORD","dataVersion":"5.1","cveMetadata":{"cveId":"CVE-2025-62496","state":"PUBLISHED","datePublished":"2025-10-16T15:52:05.654Z","dateUpdated":"2025-10-16T17:26:25.654Z","assignerShortName":"Google","assignerOrgId":"14ed7db2-1595-443d-9d34-6215bf890778","dateReserved":"2025-10-15T08:47:41.878Z"},"containers":{"cna":{"title":"Integer overflow in js_bigint_from_string in QuickJS","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."}],"affected":[{"vendor":"QuickJS","product":"QuickJS","packageName":"js_bigint_from_string","defaultStatus":"unaffected","versions":[{"version":"2025-04-26","status":"affected","lessThan":"2025-09-13","versionType":"date"}],"collectionURL":"https://bellard.org/quickjs/"}],"references":[{"url":"https://bellard.org/quickjs/Changelog"},{"url":"https://issuetracker.google.com/434193016"}],"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-190","description":"CWE-190 Integer Overflow or Wraparound","lang":"en","type":"CWE"}]}],"providerMetadata":{"shortName":"Google","orgId":"14ed7db2-1595-443d-9d34-6215bf890778","dateUpdated":"2025-10-16T15:52:05.654Z"},"credits":[{"lang":"en","type":"finder","value":"Google Big Sleep"}],"datePublic":"2025-07-24T22:00:00.000Z","impacts":[{"capecId":"CAPEC-175","descriptions":[{"lang":"en","value":"CAPEC-175 Code Inclusion"}]}],"source":{"discovery":"UNKNOWN"},"x_generator":{"engine":"Vulnogram 0.2.0"}},"adp":[{"title":"CISA ADP Vulnrichment","metrics":[{"other":{"type":"ssvc","content":{"timestamp":"2025-10-16T17:26:14.998141Z","id":"CVE-2025-62496","options":[{"Exploitation":"poc"},{"Automatable":"no"},{"Technical Impact":"total"}],"role":"CISA Coordinator","version":"2.0.3"}}}],"providerMetadata":{"shortName":"CISA-ADP","orgId":"134c704f-9b21-4f2e-91b3-4a467353bcc0","dateUpdated":"2025-10-16T17:26:25.654Z"}}]}}}