Vulnerability · Published Apr 6, 2026 · Assigned by GitHub_M

CVE-2026-34208SandboxJS: Sandbox integrity escape

Critical 10.0

In plain English

A critical-severity security flaw in SandboxJS from nyariv. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)10.0Critical

Exploit odds (30 days)0.6%top 52.0% 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 0.8.36, SandboxJS blocks direct assignment to global objects (for example Math.random = ...), but this protection can be bypassed through an exposed callable constructor path: this.constructor.call(target, attackerObject). Because this.constructor resolves to the internal SandboxGlobal function and Function.prototype.call is allowed, attacker code can write arbitrary properties into host global objects and persist those mutations across sandbox instances in the same process. This vulnerability is fixed in 0.8.36.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	@nyariv/sandboxjs	0.8.36	GHSA-2gg9-6p7w-6cpj

Affected products (as reported)

Vendor	Product	Versions
nyariv	SandboxJS	< 0.8.36

Weakness: CWE-693, CWE-915 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L

References

https://github.com/nyariv/SandboxJS/security/advisories/GHSA-2gg9-6p7w-6cpj x_refsource_CONFIRM