What is the CVSS score of CVE-2026-25881?

CVE-2026-25881 has a CVSS 3.1 base score of 9.0 (Critical). CVSS vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H. EPSS exploitation probability: 0.1%.

Which versions of Sandboxjs are affected by CVE-2026-25881?

SandboxJS versions prior to 0.8.31 contain a critical sandbox escape vulnerability that allows attackers to break out of the JavaScript sandbox and directly manipulate host system prototypes,…. A patch is available.

Is there a public PoC exploit available for CVE-2026-25881?

Yes, a public proof-of-concept exploit is available for CVE-2026-25881. Prioritise patching immediately. EPSS: 0.1%.

How to fix or mitigate CVE-2026-25881?

Within 24 hours: Identify all applications and services using SandboxJS and determine current versions in production; assess whether untrusted or user-supplied code is executed in these sandboxes. Within 7 days: Apply vendor patch upgrading SandboxJS to version 0.8.31 or later across all affected systems; test in staging environment before production deployment. Within 30 days: Conduct code review and penetration testing of patched systems to confirm sandbox escape protections are restored; review logs for any exploitation indicators dating back 90 days.

Sandboxjs CVE-2026-25881

CRITICAL

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

2026-02-09 security-advisories@github.com

GHSA-ww7g-4gwx-m7wj

RCE Sandboxjs

9.0

CVSS 3.1 · GitHub Advisory

Severity by source

GitHub Advisory PRIMARY

9.0 CRITICAL

AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Primary rating from GitHub Advisory · only source for this CVE.

CVSS VectorGitHub Advisory

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H

Attack Vector

Network

Attack Complexity

High

Privileges Required

None

User Interaction

None

Scope

Changed

Confidentiality

High

Integrity

High

Availability

High

Lifecycle Timeline

Analysis Generated

Mar 12, 2026 - 21:54 vuln.today

PoC Detected

Feb 18, 2026 - 18:07 vuln.today

Public exploit code

Patch released

Feb 18, 2026 - 18:07 nvd

Patch available

CVE Published

Feb 09, 2026 - 22:16 nvd

CRITICAL 9.0

DescriptionGitHub Advisory

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.