Vulnerability · Published Feb 6, 2026 · Assigned by GitHub_M

CVE-2026-25586SandboxJS has a Sandbox Escape via Prototype Whitelist Bypass and Host Prototype Pollution

Critical 10.0

In plain English

A critical-severity injection in SandboxJS from nyariv. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)10.0Critical

Exploit odds (30 days)0.7%top 47.0% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.29, a sandbox escape is possible by shadowing hasOwnProperty on a sandbox object, which disables prototype whitelist enforcement in the property-access path. This permits direct access to __proto__ and other blocked prototype properties, enabling host Object.prototype pollution and persistent cross-sandbox impact. This vulnerability is fixed in 0.8.29.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	@nyariv/sandboxjs	0.8.29	GHSA-jjpw-65fv-8g48

Affected products (as reported)

Vendor	Product	Versions
nyariv	SandboxJS	< 0.8.29

Weakness: CWE-74 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

References

https://github.com/nyariv/SandboxJS/security/advisories/GHSA-jjpw-65fv-8g48 x_refsource_CONFIRM
https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3 x_refsource_MISC