Out-of-Bounds Read in Samsung Escargot

Executive Summary

CVE-2026-58307 is a vulnerability in the Escargot JavaScript engine used by Samsung. It involves improper validation and handling of certain JavaScript operations that cause assertion failures and crashes. Specifically, the vulnerability leads to out-of-bounds reads and memory access violations due to incorrect management of object properties, array operations, and type conversions.

Two critical issues were identified: one causing crashes when using labeled continue statements in for-of loops due to improper iterator cleanup, and another causing segmentation faults from premature release of resources in switch-case statements with using declarations. These issues result in invalid memory accesses and engine crashes.

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Impact Analysis

This vulnerability can cause the Escargot JavaScript engine to crash or behave unpredictably when processing specially crafted JavaScript code. The crashes are due to invalid memory accesses and assertion failures, which can lead to denial of service by terminating scripts unexpectedly.

While the vulnerability does not directly lead to data confidentiality loss, it can impact the availability of applications relying on the Escargot engine by causing them to stop functioning properly.

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Detection Guidance

This vulnerability can be detected by observing crashes or assertion failures in the Escargot JavaScript engine, especially in debug builds compiled with AddressSanitizer and specific sanitization flags.

Detection involves running crafted JavaScript code patterns that trigger the vulnerability, such as those involving labeled continue statements targeting for-of loops, or using declarations in switch cases that cause segmentation faults.

Specific assertion failures to look for include checks like `!v.isEmpty()`, `isDisposableResourceRecord()`, and `spreadArray->isFastModeArray()`.

While no direct network commands are provided, testing can be performed by executing proof-of-concept JavaScript code that manipulates object properties, array operations, and type conversions to trigger crashes.

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Mitigation Strategies

The immediate mitigation step is to update the Escargot JavaScript engine to a version that includes the fixes from pull request #1586.

These fixes address the crash caused by labeled continue statements in for-of loops and the segmentation fault caused by using declarations in switch cases by improving loop label tracking and resource management.

If updating is not immediately possible, avoid running untrusted or crafted JavaScript code that uses labeled continue statements targeting for-of loops or using declarations in switch cases.

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Compliance Impact

The provided information does not specify any direct impact of CVE-2026-58307 on compliance with common standards and regulations such as GDPR or HIPAA.

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