Type Confusion in Samsung Escargot

Compliance Impact

The provided information does not specify any direct impact of this vulnerability on compliance with common standards and regulations such as GDPR or HIPAA.

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Executive Summary

This vulnerability is a type confusion issue in the Samsung Open Source Escargot JavaScript engine. It occurs when the engine mishandles array operations involving spread elements, causing confusion between different internal array types (fast and slow modes). This leads to improper memory access, potentially causing a crash or unexpected behavior.

Specifically, the bug happens in the function that defines properties on arrays using spread elements, where the code expects a fast-mode array but instead receives a slow-mode array, triggering an assertion failure and a segmentation fault.

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Impact Analysis

This vulnerability can cause the Escargot JavaScript engine to crash due to invalid memory access triggered by type confusion. Such crashes can lead to denial of service (DoS) conditions in applications relying on this engine.

Additionally, the vulnerability allows pointer manipulation, which might be exploited to alter program behavior or corrupt memory, potentially leading to further security issues.

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Detection Guidance

This vulnerability manifests as a crash or segmentation fault in the Escargot JavaScript engine when handling specific array operations involving spread elements and prototype objects.

Detection can involve monitoring for crashes or assertion failures related to array operations in Escargot, especially those triggered by scripts using spread elements in arrays.

Since the issue is a type confusion leading to memory access errors, running Escargot with UndefinedBehaviorSanitizer (UBSan) or similar memory error detection tools can help identify the problem.

No specific network commands are provided, but on the system running Escargot, you can check for crash logs or run test scripts that reproduce the issue.

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Mitigation Strategies

The primary mitigation is to update the Escargot JavaScript engine to a version including the fix committed on May 27, 2026, which adds proper validation of ArrayBuffer byte lengths and improves error handling.

Until the update is applied, avoid running untrusted or specially crafted JavaScript code that uses spread elements in arrays or manipulates ArrayBuffers in ways that could trigger the vulnerability.

Monitoring for crashes and applying patches promptly are recommended to reduce risk.

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