The vulnerability in the vm2 Node.js sandbox allows attackers to escape the isolated environment by utilizing unblocked cross-realm Symbol.for keys and missing bridge write-trap symbol checks. This flaw enables the sandboxed code to retrieve genuine cross-realm symbols, write them to host objects, and thereby control host-side behavior, leading to full remote code execution. The weakness corresponds to missing integrity checks for privileged operations, as reflected in CWE‑693.

The issue affects the patriksimek vm2 sandbox library for Node.js. Any installation of vm2 prior to version 3.11.4 is vulnerable. Versions 3.11.4 and later contain the fix.

The CVSS score of 8.7 indicates a high severity vulnerability, while the EPSS score of less than 1 % suggests a low probability of exploitation at present. The vulnerability is not listed in the CISA KEV catalog. Attackers would need the ability to execute untrusted code within a vm2 sandbox; from that point, they can leverage the escape to modify host-side objects and APIs. Based on the description, it is inferred that the attack would originate from code running inside the sandbox and involves triggering property traps that lack proper symbol checks.