JavaScript Sandboxing Flaw in SandboxJS Library by Nyariv
CVE-2026-25520

10CRITICAL

Key Information:

Vendor

Nyariv

Status
Sandboxjs
Vendor
CVE Published:
6 February 2026

What is CVE-2026-25520?

The SandboxJS library, a JavaScript sandboxing tool, has a vulnerability in versions prior to 0.8.29 that exposes a significant security risk. This flaw occurs because the return values of functions are not properly encapsulated within the sandbox environment. By leveraging methods such as Object.values or Object.entries, an attacker can retrieve an array that includes the host's Function constructor. Using Array.prototype.at, this can lead to the execution of arbitrary code outside of the intended sandbox context. This defect has been rectified in version 0.8.29, underscoring the necessity for users to update promptly to mitigate potential security threats.

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Affected Version(s)

SandboxJS < 0.8.29

References

https://github.com/nyariv/SandboxJS/security/advisories/G...
x_refsource_CONFIRM
https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c...
x_refsource_MISC

CVSS V3.1

Score:
10
Severity:
CRITICAL
Confidentiality:
High
Integrity:
High
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
None
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

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