CVE-2026-25881

Critical

Description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.31, a sandbox escape vulnerability allows sandboxed code to mutate host built-in prototypes by laundering the isGlobal protection flag through array literal intermediaries. When a global prototype reference (e.g., Map.prototype, Set.prototype) is placed into an array and retrieved, the isGlobal taint is stripped, permitting direct prototype mutation from within the sandbox. This results in persistent host-side prototype pollution and may enable RCE in applications that use polluted properties in sensitive sinks (example gadget: execSync(obj.cmd)). This vulnerability is fixed in 0.8.31.

SeverityCritical
CVSS9.0
Exploit probability—
ProductNyariv Sandboxjs
PublishedFeb 9, 2026
First seenFeb 9, 2026

How to fix

Update
  • nyariv sandboxjs0.8.31 or later
  • @nyariv/sandboxjs0.8.31 or later

Affected products

ProductAffected versionsFixed in
nyariv sandboxjsv < 0.8.310.8.31
@nyariv/sandboxjsnpmv < 0.8.310.8.31

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