CVE-2026-25587
Unknown Unknown - Not Provided
Prototype Pollution in SandboxJS Map.prototype Enables Sandbox Escape

Publication date: 2026-02-06

Last updated on: 2026-02-18

Assigner: GitHub, Inc.

Description
SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, as Map is in SAFE_PROTOYPES, it's prototype can be obtained via Map.prototype. By overwriting Map.prototype.has the sandbox can be escaped. This vulnerability is fixed in 0.8.29.
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Meta Information
Published
2026-02-06
Last Modified
2026-02-18
Generated
2026-06-16
AI Q&A
2026-02-06
EPSS Evaluated
2026-06-14
NVD
CVE-2026-25587
EUVD
EUVD-2026-5590
Affected Vendors & Products
Showing 1 associated CPE
Vendor Product Version / Range
nyariv sandboxjs to 0.8.29 (exc)
Helpful Resources
Exploitability
CWE
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KEV
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CWE ID Description
CWE-94 The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.
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Impact Analysis

Exploiting this vulnerability allows an attacker to escape the sandbox, which is intended to isolate and restrict code execution. This can lead to complete compromise of the system where the sandbox is used, including full control over confidentiality, integrity, and availability of the affected environment.

Compliance Impact

I don't know

Detection Guidance

I don't know

Mitigation Strategies

To mitigate this vulnerability, upgrade the SandboxJS library to version 0.8.29 or later where the issue is fixed.

Executive Summary

This vulnerability exists in SandboxJS, a JavaScript sandboxing library, in versions prior to 0.8.29. The issue arises because the Map object is included in SAFE_PROTOTYPES, allowing its prototype to be accessed via Map.prototype. An attacker can exploit this by overwriting the Map.prototype.has method, which enables them to escape the sandbox environment.

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