CVE-2026-92959

vm2 before 3.11.8 allowAsync Bypass via Promise Thenable

Published Sep 17, 2026 CVSS 4.0 · 7.1 High EPSS < 1% KEV · Not listed
Description
vm2 before 3.11.8 does not fully enforce the allowAsync: false option in VM and NodeVM. While localPromise.prototype.then is replaced with a handler that throws 'Async not available', the sandbox's Promise static methods (Promise.resolve, Promise.all, Promise.race, Promise.any, and Promise.allSettled) still assimilate attacker-supplied thenables: native promise resolution performs PromiseResolveThenableJob and invokes the sandboxed code's then method in a microtask without passing through the patched then, so the async restriction is never applied. As a result, sandboxed script can schedule work that runs after VM.run() or NodeVM.run() has returned and outside the configured timeout, continuing to execute after the host believes execution is complete.

Remediation

No solution or workaround provided in the CVE record

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-f8gf-w286-fmq2 vm2: `allowAsync: false` can be bypassed through Promise thenable assimilation in VM and NodeVM
History
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'poc', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
First Time appeared Patriksimek
Patriksimek vm2
Vendors & Products Patriksimek
Patriksimek vm2
Type Values Removed Values Added
Description vm2 before 3.11.8 does not fully enforce the allowAsync: false option in VM and NodeVM. While localPromise.prototype.then is replaced with a handler that throws 'Async not available', the sandbox's Promise static methods (Promise.resolve, Promise.all, Promise.race, Promise.any, and Promise.allSettled) still assimilate attacker-supplied thenables: native promise resolution performs PromiseResolveThenableJob and invokes the sandboxed code's then method in a microtask without passing through the patched then, so the async restriction is never applied. As a result, sandboxed script can schedule work that runs after VM.run() or NodeVM.run() has returned and outside the configured timeout, continuing to execute after the host believes execution is complete.
Title vm2 before 3.11.8 allowAsync Bypass via Promise Thenable
Weaknesses CWE-693
References
Metrics cvssV3_1

{'score': 7.1, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:H'}

cvssV4_0

{'score': 7.1, 'vector': 'CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/SA:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
VulnCheck
Published
Updated
Sep 21, 2026, 8:41 PM
Reserved
Sep 17, 2026, 12:43 PM
Status
Deferred
Published
Sep 17, 2026, 2:18 PM
Modified
Sep 21, 2026, 9:17 PM
Severity
Important
Public date
Sep 17, 2026, 1:46 PM