JavaScript Sandboxing Vulnerability in SandboxJS Library by Nyariv

CVE-2026-26954

What is CVE-2026-26954?

CVE-2026-26954 is a vulnerability found in the SandboxJS library, a JavaScript sandboxing solution developed by Nyariv. This library is designed to securely execute untrusted JavaScript code by isolating it from the host environment, protecting the system from potentially harmful actions. Prior to the release of version 0.8.34, a flaw was identified that allowed unauthorized access to certain arrays containing Function objects, which could facilitate escaping the confines of the sandbox environment. Exploiting this vulnerability could enable attackers to bypass the intended restrictions of the sandbox, leading to unauthorized execution of code and exposing the host system to various malicious activities. The immediate technical concern is the ability to construct objects that can leak sensitive information or allow the execution of arbitrary functions, severely compromising the integrity and confidentiality of the environment in which the library is deployed.

Potential impact of CVE-2026-26954

1. Unauthorized Code Execution: The vulnerability can lead to the execution of malicious code outside the intended sandbox, potentially allowing attackers to control or manipulate the host system.

2. Data Exposure: By escaping the sandbox, attackers may gain access to sensitive data held within the application or the host environment, increasing the risk of data breaches.

3. Compromise of System Integrity: The ability to bypass sandboxing protections can lead to further exploitation of the host system, enabling attackers to deploy additional malicious software or manipulate system processes.

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