{"id":"CVE-2025-62496","details":"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-\u003etab array.","modified":"2026-04-10T05:33:06.336331Z","published":"2025-10-16T16:15:40.260Z","references":[{"type":"ADVISORY","url":"https://bellard.org/quickjs/Changelog"},{"type":"REPORT","url":"https://issuetracker.google.com/434193016"}],"affected":[{"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-62496.json","unresolved_ranges":[{"events":[{"introduced":"0"},{"fixed":"2025-09-13"}]}]}}],"schema_version":"1.7.5","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}