CVE-2026-44000 | vm2: sandbox boundary bypass via host Promise resolution preserving host object identity

Exp

vm2 is an open source vm/sandbox for Node.js. Prior to 3.11.0, a sandbox boundary violation in vm2 allows host object identity to cross into the sandbox through host Promise resolution. When a host-side Promise that resolves to a host object is exposed to the sandbox, the value delivered to the sandbox .then() callback preserves host identity. This allows the sandbox to interact with the host object directly, including performing identity checks using host-side WeakMap and mutating host object state from inside the sandbox. This behavior occurs because the Promise fulfillment wrapper uses ensureThis() instead of the stronger cross-realm conversion path (from() / proxy wrapping). If no prototype mapping is found, ensureThis() returns the original object. As a result, objects resolved by host Promises can cross the sandbox boundary without proper isolation. This vulnerability is fixed in 3.11.0.

Published: 2026-05-13 Last update: 2026-05-14 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2026-44000 is rated Exploit Available (50/100): CVSS Medium severity, with low exploitation likelihood (EPSS 0.04%). 1 public exploit reference(s) are indexed (Exploit-DB). Public exploits are available—assess exposure, apply mitigations, and prioritize patching.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Public exploit references (Exploit-DB) for CVE-2026-44000

EDB-ID Source Kind Published Link
— nvd_ref exploit_tag Exploit-DB ↗

Exploit prediction scoring system (EPSS) score for CVE-2026-44000

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-05-14 — 0.04% —

Full EPSS history (1 record total)

Common vulnerability scoring system (CVSS) metrics for CVE-2026-44000

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
6.5 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 2.5 [email protected]
7.2 3.1 HIGH
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:L/A:N Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:C)
Breaking this can reach past the original component and bite other resources—bigger blast radius.
Confidentiality (C:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:L)
Attackers could change some data, but it’s limited—not everything goes.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 2.7 [email protected]

Weakness enumeration for CVE-2026-44000

GitHub Security Advisory for CVE-2026-44000

GHSA-mpf8-4hx2-7cjg · Severity: medium · Ecosystem: npm — vm2 Host Promise Resolution Preserves Object Identity Across Sandbox Boundary

Affected software / configurations for CVE-2026-44000

Vendor Product Version Raw CPE
vm2_project vm2 < 3.11.0 cpe:2.3:a:vm2_project:vm2:*:*:*:*:*:node.js:*:*

References for CVE-2026-44000

cvelogic Threat Intelligence