Isolated-vm Flaw Lets Sandboxed JavaScript Escape to Host for Potential RCE
Critical type-confusion flaw in isolated-vm Node.js sandbox (GHSA-864f-rcv7-6rh4) enables guest-to-host escape and potential RCE; fixed in 6.2.0 and 7.0.1.
Endor Labs researcher Cristian-Alexandru Staicu found a type confusion in the ExternalCopy component's handling of the transferList option in isolated-vm, letting sandboxed JavaScript corrupt host-process memory and escalate from controlled-address crashes to full control-flow hijack of the host, i.e., potential remote code execution. The flaw, tracked as GHSA-864f-rcv7-6rh4 with no CVE yet, affects all versions through 7.0.0 of the library, which sees nearly 1 million npm downloads weekly. It was patched in versions 6.2.0 and 7.0.1 released earlier in August 2026, and full exploit details are withheld to prevent attacks. The V8 Isolate boundary itself held; the failure was in the C++ marshalling code bridging host and guest.
- Type confusion in ExternalCopy's transferList handling corrupts host-process memory.
- Impact ranges from reliable sandboxed denial-of-service to host control-flow hijack.
- Patched in isolated-vm 6.2.0 and 7.0.1; users should upgrade immediately.
- Package receives nearly 1 million npm downloads per week.
- Vendors
- Endor Labs
- Products
- isolated-vmNode.jsV8
- Organizations
- Endor Labs
From the original article
2 min read at thehackernews.com
Ravie Lakshmanan Aug 20, 2026 Vulnerability / Application Security Cybersecurity researchers have disclosed a critical security flaw in isolated-vm , a popular open-source sandbox with more than 2,900 stars and 190 forks on GitHub, that could allow attackers to escape the confines of the isolated environment.
By @TheHackersNews · thehackernews.com
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