{"id":"CVE-2025-62496","url":"https://www.cyber-defence.io/tools/cve/CVE-2025-62496","generatedAt":"2026-10-28T09:42:31.436Z","title":"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.","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.","published":"2025-10-16T16:15:40.000Z","lastModified":"2026-10-19T17:10:00.000Z","status":"Analyzed","sourceIdentifier":"cve-coordination@google.com","cvss":{"version":"4.0","score":7.1,"severity":"HIGH","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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/M"},"cwe":["CWE-190"],"affected":["quickjs project/quickjs"],"epss":{"score":0.0048,"percentile":0.41182,"date":"2026-10-27","history":[]},"kev":{"listed":false},"exploits":{"count":0,"verified":false,"firstPublished":null,"source":"Exploit-DB (https://gitlab.com/exploit-database/exploitdb)","entries":[]},"verdict":{"level":"high","text":"High impact if exploited, but EPSS currently rates exploitation as unlikely (0.48%). Schedule it in the normal patch cycle and watch for a rise in EPSS or a public exploit."},"changes":[],"references":[{"url":"https://bellard.org/quickjs/Changelog","tags":["Release Notes"],"source":"cve-coordination@google.com"},{"url":"https://issuetracker.google.com/434193016","tags":["Exploit","Issue Tracking"],"source":"cve-coordination@google.com"}],"sources":{"nvd":"https://nvd.nist.gov/vuln/detail/CVE-2025-62496","epss":"https://www.first.org/epss/","kev":"https://www.cisa.gov/known-exploited-vulnerabilities-catalog","exploitdb":"https://www.exploit-db.com/"},"licence":"CC BY 4.0 — link back to the CVE Explorer if you publish the results; upstream data remains subject to its own terms."}