{"cve":"CVE-2025-62496","nvd":{"published":"2025-10-16T16:15:40.260","modified":"2026-10-19T17:10:00.173","status":"Analyzed","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.","cvss_v4":{"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","score":7.1},"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.8},"cwes":["CWE-190"],"references":["https://bellard.org/quickjs/Changelog","https://issuetracker.google.com/434193016"],"products":["quickjs_project:quickjs"],"source":"nvd","synced_at":"2026-10-19T22:12:35.277909958+00:00"},"epss":{"cve":"CVE-2025-62496","score":0.0048,"percentile":0.41088,"date":"2026-10-25"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}