A prototype pollution vulnerability exists in @nyariv/sandboxjs versions <= 0.8.23, allowing attackers to inject arbitrary properties into Object.prototype via crafted JavaScript code. This can result in a denial-of-service (DoS) condition or, under certain conditions, escape the sandboxed environment intended to restrict code execution. The vulnerability stems from insufficient prototype access checks in the sandbox’s executor logic, particularly in the handling of JavaScript function objects returned.
https://www.vulncheck.com/advisories/nyariv-sandboxjs-prototype-pollution-sandbox-escape-dos
https://www.npmjs.com/package/@nyariv/sandboxjs
https://github.com/nyariv/SandboxJS/issues/31
https://gist.github.com/Hagrid29/9df27829a491080f923c4f6b8518d7e3
Published: 2025-07-31
Updated: 2026-04-15
Base Score: 7.5
Vector: CVSS2#AV:N/AC:L/Au:N/C:P/I:P/A:P
Severity: High
Base Score: 9.8
Vector: CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Severity: Critical
Base Score: 7
Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:N/VC:N/VI:H/VA:H/SC:N/SI:N/SA:N
Severity: High
EPSS: 0.00054