What is CVE-2026-25881?

CVE-2026-25881 is a critical-severity vulnerability in Nyariv Sandboxjs, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 9.1/10. Published 2026-02-09.

How severe is CVE-2026-25881?

Critical severity. CVSS v3 base score is 9.1 out of 10.

Prototype Pollution in Nyariv Sandboxjs

CVE-2026-25881

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…

Vulnerability class: Prototype Pollution

EPSS: 0.001 (18.1th percentile) — read the EPSS interpretation.

CVSS v3 metric

CVSS v3 base score 9.1 (Critical). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H.

Affected products

Nyariv Sandboxjs — versions < 0.8.31

Weakness classification (CWE)

CWE-1321 — Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution)

References

https://github.com/nyariv/SandboxJS/security/advisories/GHSA-ww7g-4gwx-m7wj (x_refsource_CONFIRM)
https://github.com/nyariv/SandboxJS/commit/f369f8db26649f212a6a9a2e7a1624cb2f705b53 (x_refsource_MISC)

Frequently asked questions

What is CVE-2026-25881?: CVE-2026-25881 is a critical-severity vulnerability in Nyariv Sandboxjs, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). CVSS score: 9.1/10. Published 2026-02-09.
How severe is CVE-2026-25881?: Critical severity. CVSS v3 base score is 9.1 out of 10.