Vulnerability 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.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Nyariv | Sandboxjs | < 0.8.29 |
Related Weaknesses (CWE)
References
- https://github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e4Patch
- https://github.com/nyariv/SandboxJS/security/advisories/GHSA-jjpw-65fv-8g48ExploitVendor Advisory
- https://github.com/nyariv/SandboxJS/security/advisories/GHSA-jjpw-65fv-8g48ExploitVendor Advisory
FAQ
What is CVE-2026-25586?
CVE-2026-25586 is a vulnerability with a CVSS score of 10.0 (CRITICAL). 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 prope...
How severe is CVE-2026-25586?
CVE-2026-25586 has been rated CRITICAL with a CVSS base score of 10.0/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-25586?
Check the references section above for vendor advisories and patch information. Affected products include: Nyariv Sandboxjs.