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Mallory
CriticalPublic exploit

Prototype Pollution in vm2 sandbox bridge

IdentifiersCVE-2026-44005CWE-1321· Improperly Controlled Modification…

CVE-2026-44005 is a critical sandbox-isolation flaw in vm2, the Node.js vm/sandbox library. Affected versions 3.9.6 through 3.10.5 expose mutable proxies to real host-realm intrinsic prototypes through vm2's bridge layer. Sandbox-originated writes are then forwarded into the underlying host objects via otherReflectSet() and otherReflectDefineProperty(). As a result, attacker-controlled JavaScript executing inside a default VM or inherited NodeVM can mutate shared host prototypes, including Object.prototype, Array.prototype, and Function.prototype, from within the sandbox. This breaks the intended isolation boundary and enables prototype pollution of host-side intrinsics shared by the Node.js process. The issue is fixed in vm2 3.11.0.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows untrusted code running inside the vm2 sandbox to modify shared host intrinsic prototypes, undermining the integrity of the entire Node.js process. Because Object.prototype, Array.prototype, and Function.prototype are process-wide primitives, pollution can alter application behavior globally, corrupt security assumptions, interfere with control flow, and cause denial-of-service conditions. The provided CVSS vector indicates high integrity impact and high availability impact, with no listed confidentiality impact.

Mitigation

If you can’t patch tonight, do this now.

If immediate patching is not possible, avoid executing untrusted JavaScript in affected vm2 versions. Reduce exposure by disabling or suspending features that allow attacker-supplied code to run in default VM or inherited NodeVM contexts, and isolate such workloads at a stronger boundary than a JavaScript-level sandbox where feasible. The supplied context does not provide a vendor-specific workaround short of upgrading.

Remediation

Patch, then assume compromise.

Upgrade vm2 to version 3.11.0 or later. The provided content states that the flaw is fixed in vm2 3.11.0. More generally, environments executing untrusted JavaScript should ensure all vm2 instances are updated beyond the affected range 3.9.6 through 3.10.5.
PUBLIC EXPLOITS

Exploits

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VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

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VendorProductType
Vm2 ProjectVm2application

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What this page doesn’t show

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Exposure mapping

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Threat actor evidence

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Associated malware

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Detection signatures

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Vendor-by-vendor mapping

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Social activity3

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