CVE-2025-62494
Severity CVSS v4.0:
HIGH
Type:
CWE-704
Incorrect Type Conversion or Cast
Publication date:
16/10/2025
Last modified:
29/10/2025
Description
A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine.<br />
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* The code first checks if the left-hand operand is a string.<br />
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* 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).<br />
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* 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).<br />
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* The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string.<br />
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This 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.
Impact
Base Score 4.0
7.10
Severity 4.0
HIGH
Base Score 3.x
8.80
Severity 3.x
HIGH
Vulnerable products and versions
| CPE | From | Up to |
|---|---|---|
| cpe:2.3:a:quickjs_project:quickjs:*:*:*:*:*:*:*:* | 2025-09-13 (excluding) |
To consult the complete list of CPE names with products and versions, see this page