CVE-2026-34217: SandboxJS has a Sandbox Escape via Prop Object Leak in New Handler

Severity: high (CVSS 7.2 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2026-04-06 · updated 2026-10-26
Weakness: CWE-668

Description

SandboxJS is a JavaScript sandboxing library. Prior to 0.8.36, a scope modification vulnerability exists in @nyariv/sandboxjs. The vulnerability allows untrusted sandboxed code to leak internal interpreter objects through the new operator, exposing sandbox scope objects in the scope hierarchy to untrusted code; an unexpected and undesired exploit. While this could allow modifying scopes inside the sandbox, code evaluation remains sandboxed and prototypes remain protected throughout the execution. This vulnerability is fixed in 0.8.36.

Affected products

nyariv SandboxJS: before 0.8.36 — fixed in 0.8.36

How to fix

Upgrade to a fixed version: nyariv SandboxJS 0.8.36. Check the vendor advisory for mitigations.

References

Get alerted when CVE-2026-34217 or the next vulnerability affects your stack