CVE-2026-43898: Nyariv Sandboxjs

Critical severity, CVSS 10.0. EPSS: 0.6% chance of exploitation in the next 30 days.

SandboxJS is a JavaScript sandboxing library. Prior to 0.9.6, sandbox-defined functions expose Function.caller, allowing sandboxed code to recover the internal LispType.Call runtime callback. That callback can then be invoked with attacker-controlled fake context and obj values to extract blocked host statics, recover the real host Function constructor, and execute arbitrary host JavaScript. This vulnerability is fixed in 0.9.6.

Affected products

• Nyariv Sandboxjs: before 0.9.6 (fixed in 0.9.6)

Published 2026-05-28. Last modified 2026-06-17.