Host code execution via Promise species hijack
Published Sep 18, 2026 · Updated Sep 18, 2026
Sandbox escape in Patrik Simek vm2 3.12.0 and earlier allows attackers to execute arbitrary code on the host through a rejected Promise. The bridge wraps only function-valued rejection handlers, while host Promise methods bypass sandbox Promise species neutralization, letting a missing onRejected handler deliver an unsanitized host rejection through attacker-controlled Symbol.species. Exploitation requires an embedder-exposed host-realm Promise that rejects with a host-pivotable value; successful escape grants host-process authority.
Summary
What happened
Sandbox escape in Patrik Simek vm2 3.12.0 and earlier allows attackers to execute arbitrary code on the host through a rejected Promise. The bridge wraps only function-valued rejection handlers, while host Promise methods bypass sandbox Promise species neutralization, letting a missing onRejected handler deliver an unsanitized host rejection through attacker-controlled Symbol.species. Exploitation requires an embedder-exposed host-realm Promise that rejects with a host-pivotable value; successful escape grants host-process authority.
The record
- CVE
- CVE-2026-93606
- Published
- Sep 18, 2026
- Updated
- Sep 18, 2026
- Vendor
- Patrik Simek
- Product
- vm2
- Classifications
- CWE-693, T1611
- Attack vector
- network
- Privileges
- unauthenticated
Timeline
How it unfolded
- Sep 18, 2026CVE publishedPublication date reported by the CVE source.
- Sep 18, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <3.12.1
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Activity data is delayed. The latest report is Sep 28, 2026.
Public exploit references
- Upstream host Promise Symbol.species sandbox-escape PoCproof of concept · demonstrated
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Technologies
Your stack
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