Prototype Pollution in Nyariv Sandboxjs
CVE-2025-34146
A prototype pollution vulnerability exists in @nyariv/sandboxjs versions <= 0.8.23, allowing attackers to inject arbitrary properties into Object.prototype via crafted JavaScript code. This can result in a denial-of-service (DoS) condition or, under certain conditions, escape the sandboxed environment intended to restrict code execution. The vulnerability stems from insufficient prototype access checks in the sandbox’s executor logic, particularly in the handling of JavaScript function objects returned.
Vulnerability class: Prototype Pollution
Published · last modified .
EPSS exploit prediction
EPSS: 0.002 (9.2th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 9th percentile — 9.2% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: 0.000
Affected products
- Nyariv Sandboxjs — versions 0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- gist.github.com/Hagrid29/9df27829a491080f923c4f6b8518d7e3 (issue-tracking, exploit)
- github.com/nyariv/SandboxJS/issues/31 (issue-tracking, vendor-advisory, patch)
- www.npmjs.com/package/@nyariv/sandboxjs (product)
- www.vulncheck.com/advisories/nyariv-sandboxjs-prototype-pollution-sandbox-escap… (third-party-advisory)
Frequently asked questions
- What is CVE-2025-34146?
- CVE-2025-34146 is a vulnerability in Nyariv Sandboxjs, classified under Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution). Published 2025-07-31.
- Is CVE-2025-34146 known to be exploited?
- 1 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.