CVE-2026-34208 | SandboxJS is a JavaScript sandboxing library. Prior to 0.8.3… | CVSS 10.0 CRITICAL

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.

Metadata

CVE ID: CVE-2026-34208
State: PUBLISHED
Assigner: GitHub_M
Reserved: 2026-03-26 15:57 UTC
Published: 2026-04-06 15:09 UTC
Last updated: 2026-04-06 18:39 UTC
Primary CWE: CWE-693
CWE-693: Protection Mechanism Failure
Vendor / Product: nyariv / SandboxJS
Sources: cve.org · NVD

Severity & Metrics

10.0 CRITICAL CVSS 3.1

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

SSVC — CISA Coordinator

Exploitation: PoC
Automatable: yes
Tech. Impact: total

Affected products (1)

Vendor	Product	Platform	Versions
nyariv	SandboxJS	—	< 0.8.36

Weakness (CWE)

CWE	Source	Description
CWE-693	cna	CWE-693: Protection Mechanism Failure
CWE-915	cna	CWE-915: Improperly Controlled Modification of Dynamically-Determined Object Attributes

CVSS scores (1)

Score	Severity	Version	Source	Vector
10.0	CRITICAL	3.1	cna	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:L

References (1)

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