SandboxJS has a sandbox escape via Function.caller leakage of internal call op — CVE-2026-43898

Summary

### Summary 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. ### Details The vulnerability is in the property access logic…

Product

npm: @nyariv/sandboxjs

What to do

General, cautious steps (verify details in the official source):

• Prioritize patching or mitigation immediately (treat as actively risky).
• Identify affected product versions in your inventory and verify whether you are impacted.
• Apply vendor patches/updates or recommended mitigations as soon as available.
• Read the official advisory for exact affected versions and remediation steps.

Official advisory

• Read the official source
• CVE Record
• NVD

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