CVE-2026-26954: SandboxJS has a Sandbox Escape

Severity: critical (CVSS 10.0 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-03-13 · updated 2026-06-17
Weakness: CWE-94

Description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.34, it is possible to obtain arrays containing Function, which allows escaping the sandbox. Given an array containing Function, and Object.fromEntries, it is possible to construct {[p]: Function} where p is any constructible property. This vulnerability is fixed in 0.8.34.

Affected products

nyariv SandboxJS: before 0.8.34 — fixed in 0.8.34

How to fix

Upgrade to a fixed version: nyariv SandboxJS 0.8.34. Check the vendor advisory for mitigations.

References

https://github.com/nyariv/SandboxJS/security/advisories/GHSA-6r9f-759j-hjgv
https://github.com/nyariv/SandboxJS/security/advisories/GHSA-6r9f-759j-hjgv

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