Critical severityNVD Advisory· Published Feb 6, 2026· Updated Feb 6, 2026
SandboxJS has a Sandbox Escape via Prototype Whitelist Bypass and Host Prototype Pollution
CVE-2026-25586
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.
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Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
@nyariv/sandboxjsnpm | < 0.8.29 | 0.8.29 |
Affected products
2Patches
Vulnerability mechanics
References
4- github.com/advisories/GHSA-jjpw-65fv-8g48ghsaADVISORY
- nvd.nist.gov/vuln/detail/CVE-2026-25586ghsaADVISORY
- github.com/nyariv/SandboxJS/commit/67cb186c41c78c51464f70405504e8ef0a6e43c3ghsax_refsource_MISCWEB
- github.com/nyariv/SandboxJS/security/advisories/GHSA-jjpw-65fv-8g48ghsax_refsource_CONFIRMWEB
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