{"cve":"CVE-2025-62494","nvd":{"published":"2025-10-16T16:15:39.943","modified":"2026-10-19T16:10:00.260","status":"Analyzed","description":"A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine.\n\n  *  The code first checks if the left-hand operand is a string.\n\n\n  *  It then attempts to convert the right-hand operand to a primitive value using JS_ToPrimitiveFree. This conversion can trigger a callback (e.g., toString or valueOf).\n\n\n  *  During this callback, an attacker can modify the type of the left-hand operand in memory, changing it from a string to a different type (e.g., an object or an array).\n\n\n  *  The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string.\n\n\nThis mismatch between the assumed type (string) and the actual type allows an attacker to control the data structure being processed by the concatenation logic, resulting in a type confusion condition. This can lead to out-of-bounds memory access, potentially resulting in memory corruption and arbitrary code execution in the context of the QuickJS runtime.","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-704"],"references":["https://bellard.org/quickjs/Changelog","https://issuetracker.google.com/434193023"],"products":["quickjs_project:quickjs"],"source":"nvd","synced_at":"2026-10-19T22:12:35.277909958+00:00"},"epss":{"cve":"CVE-2025-62494","score":0.00514,"percentile":0.43513,"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."]}