{"id":"CVE-2025-62494","details":"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.","modified":"2026-04-10T05:33:07.437092Z","published":"2025-10-16T16:15:39.943Z","references":[{"type":"ADVISORY","url":"https://bellard.org/quickjs/Changelog"},{"type":"REPORT","url":"https://issuetracker.google.com/434193023"}],"affected":[{"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2025-62494.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"}]}