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

May 11, 2026 (updated June 9, 2026)

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.

References

github.com/advisories/GHSA-g8f2-4f4f-5jqw
github.com/nyariv/SandboxJS/commit/826865251232611ec94078bab5a18ec875dad4a5
github.com/nyariv/SandboxJS/security/advisories/GHSA-g8f2-4f4f-5jqw
nvd.nist.gov/vuln/detail/CVE-2026-43898

Code Behaviors & Features

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