{"id":"DEBIAN-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.  The function calculates the necessary number of bits (n_bits) required to store the BigInt using the formula:  $$\\text{n\\_bits} = (\\text{n\\_digits} \\times 27 + 7) / 8 \\quad (\\text{for radix 10})$$    *  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-\u003etab array.","modified":"2026-09-01T20:05:55.488479349Z","published":"2025-10-16T16:15:40.260Z","upstream":["CVE-2025-62496"],"references":[{"type":"ADVISORY","url":"https://security-tracker.debian.org/tracker/CVE-2025-62496"}],"affected":[{"package":{"name":"quickjs","ecosystem":"Debian:13","purl":"pkg:deb/debian/quickjs?arch=source&distro=trixie"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.04.26-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-62496.json"}},{"package":{"name":"quickjs","ecosystem":"Debian:14","purl":"pkg:deb/debian/quickjs?arch=source&distro=forky"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"}]}],"versions":["2025.04.26-1"],"ecosystem_specific":{"urgency":"not yet assigned"},"database_specific":{"source":"https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2025-62496.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V3","score":"CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"}]}