Security readout for executives and security teams
Plain-English summary
CVE-2021-23555 affects the Node.js vm2 sandbox package before 3.9.6. A sandbox escape could let code meant to be isolated run arbitrary code on the host system. Business urgency is high where vm2 handles untrusted or customer-controlled JavaScript.
Executive priority
Treat as urgent for any product using vm2 to isolate untrusted code. The worst-case impact is host-level arbitrary code execution, which can compromise data, service integrity, and availability.
Technical view
The issue is a vm2 sandbox bypass caused by direct access to host Error objects generated by Node internals during stack trace generation. The CVSS 3.1 score is 9.8, with network attack vector, no required privileges, no user interaction, and high confidentiality, integrity, and availability impact.
Likely exposure
Exposure is limited to applications that include vm2 before 3.9.6. Risk is greatest where vm2 executes untrusted scripts, plugin logic, workflow code, rules, templates, or user-supplied JavaScript.
Exploitation context
The source bundle does not show CISA KEV listing or cited evidence of active exploitation. The CVSS vector and exploit maturity signal indicate practical exploitability, but active exploitation should not be assumed from these sources alone.
Researcher notes
Focus triage on dependency reachability and trust boundaries. The vulnerability matters most when attacker-controlled code can trigger vm2 execution. The bundle names vm2 before 3.9.6 and includes a fixing commit reference, but provides no affected CPEs.
Mitigation direction
- Upgrade vm2 to version 3.9.6 or later where the package is used.
- Check vendor and package maintainer guidance for any later security recommendations.
- Disable or restrict untrusted JavaScript execution until affected deployments are remediated.
- Prioritize internet-facing or multi-tenant services that evaluate customer-controlled code.
Validation and detection
- Inventory package manifests and lockfiles for vm2 versions earlier than 3.9.6.
- Identify services where vm2 processes untrusted or externally influenced JavaScript.
- Confirm deployed artifacts match the remediated dependency version, not only source files.
- Review sandbox escape regression tests without reproducing exploit payloads.
Public sources used
Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.
Conservative CVE-to-ATT&CK context
These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.
ATT&CK lookup starting points
Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.
Execution behavior lookup
The CVE wording references code or command execution, so execution technique review may help defensive triage. This is a Glexia inferred lookup path, not an official MITRE, ATT&CK, or CVE Program mapping.
Open ATT&CK lookupCVE-2021-23555 mapping review
Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.
Open ATT&CK lookup- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Known Exploited
- No
- Published
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P
CNA and ADP enrichment extracted from CVE v5
These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.
CVSS vector scores
1 official scoreWe collect every scored CVSS vector available in the official CNA and ADP containers. When more than one version is present, the table keeps the source vectors side by side instead of collapsing them into the highest score.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P3.95.9Primary CVE scoreVulnerability scoring details
Base CVSS 3.1 score
9.8CriticalVector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H/E:P
Source materials
- CVE List V5 sourceCVE List V5
- https://snyk.io/vuln/SNYK-JS-VM2-2309905CVE reference · x_refsource_MISC
- https://github.com/patriksimek/vm2/commit/532120d5cdec7da8225fc6242e154ebabc63fe4dCVE reference · x_refsource_MISC
Products and packages named in the record
CWE details
CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.