* The code first checks if the left-hand operand is a string.
* 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).
* 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).
* The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string.
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.
Metrics
Affected Vendors & Products
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No advisories yet.
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
Thu, 16 Oct 2025 18:15:00 +0000
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ssvc
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Thu, 16 Oct 2025 16:00:00 +0000
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| Description | A type confusion vulnerability exists in the handling of the string addition (+) operation within the QuickJS engine. * The code first checks if the left-hand operand is a string. * 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). * 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). * The code then proceeds to call JS_ConcatStringInPlace, which still treats the modified left-hand value as a string. 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. | |
| Title | Type confusion in string addition in QuickJS | |
| Weaknesses | CWE-704 | |
| References |
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| Metrics |
cvssV4_0
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MITRE
Status: PUBLISHED
Assigner: Google
Published:
Updated: 2025-10-16T17:46:39.174Z
Reserved: 2025-10-15T08:47:41.878Z
Link: CVE-2025-62494
Vulnrichment
Updated: 2025-10-16T17:46:23.878Z
NVD
Status : Received
Published: 2025-10-16T16:15:39.943
Modified: 2025-10-16T16:15:39.943
Link: CVE-2025-62494
Redhat
No data.
OpenCVE Enrichment
No data.