Critical isolated-vm Sandbox Escape Flaw Could Lead to Remote Code Execution

Cybersecurity researchers have disclosed a critical security flaw in isolated-vm, a popular open-source Node.js sandbox library with over 2,900 stars on GitHub. The vulnerability, tracked as GHSA-864f-rcv7-6rh4, allows attackers to escape the sandbox and potentially achieve remote code execution on the host system.

The flaw resides in the ExternalCopy component, which is used to serialize JavaScript objects between the host and guest isolates. A type confusion in the handling of the transferList option enables code running inside the sandbox to corrupt memory in the host process. Endor Labs researcher Cristian-Alexandru Staicu demonstrated a full guest-to-host sandbox escape, escalating from a controlled-address crash to hijacking the host’s control flow.

Successful exploitation can cause a denial-of-service via a segmentation fault or lead to remote code execution. The vulnerability affects all versions of isolated-vm up to and including 7.0.0, with patches released in versions 6.2.0 and 7.0.1. Users are strongly advised to update to the latest version to mitigate the risk.

Notably, the V8 Isolate boundary itself remained intact; the flaw was in the C++ glue code that marshals values across the boundary. The full exploit details have been withheld to prevent malicious use.