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Full vulnerability report · 2026
CVE-2026-93603High confidence

vm2 before 3.12.1 Sandbox Escape RCE via Non-Strict Host Function

patriksimek · vm2

Official source article: GitHub GHSA-J89J-5M6R-CR2Q ↗. Check the applicable product and release in the original source.

10.0CriticalCVSS 4.0
Recommended action
Patch only the product branches with a verified fix

Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 5 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
R
Operational reassessment

Published severity in operational context

Open reassessment dashboard →
Published severityCriticalOperational priority:Critical, unchanged from published severity.unchanged

Evidence used

  • No CISA KEV confirmation is currently recorded.
  • A structured source references public exploit or proof-of-concept material.
  • The selected CVSS metric records a network-reachable, unauthenticated path with no user interaction.
  • EPSS is 0.73% for the current model date.

Compensating controls

  • Validate the affected product branch and deploy the verified fixed release.
  • Restrict the affected network interface to trusted sources where business-safe.
  • Increase monitoring for the attack path and post-exploitation behaviour described in the report.

Verification

  1. Confirm that the asset runs patriksimek vm2 and falls inside the recorded affected range.
  2. Verify the installed build against the product-specific fixed version after deployment.
  3. Validate exposure, authentication requirements and compensating controls in the actual environment.
  4. Reopen this reassessment when CVSS, KEV, EPSS, exploit evidence or remediation changes.
Mitigation target: Within 3 daysRemediation target: Within 90 days

This automated reassessment organises public evidence. It does not know asset exposure, business impact or control effectiveness and does not replace CVSS or a human risk decision.

Cross-source reconciliation

Remediation availability differs by product scope

Verified remediation exists for at least one product or source, but 5 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Direct vendor intelligence

Authoritative vendor CSAF and VEX advisories

Structured product status and remediation from the issuing vendor. Product-state explanations are always visible; large lists can be searched or downloaded.

1 current
CVE-2026-93603 · CSAF 2.0 · revision 3 · finalRed Hat Product Securityvm2: vm2 before 3.12.1 Sandbox Escape RCE via Non-Strict Host Function
5 known affected

The vendor explicitly identifies these products as affected by this CVE.

  • rhdh/red-hat-developer-hub-backstage-plugin-lightspeed-backend as a component of Red Hat Developer Hub
  • rhdh/red-hat-developer-hub-backstage-plugin-orchestrator-backend as a component of Red Hat Developer Hub
  • rhdh/rhdh-hub-rhel9 as a component of Red Hat Developer Hub
  • ansible-automation-platform/automation-portal as a component of Self-service automation portal 2
  • ansible-automation-platform/bootc-automation-portal-rhel9 as a component of Self-service automation portal 2
Summary
A flaw was found in vm2. This vulnerability allows an attacker who can execute untrusted script within the sandbox to achieve arbitrary code execution on the underlying host system by escaping sandbox containment. The issue occurs because vm2 fails to properly handle function calls lacking an object receiver, causing the JavaScript runtime to expose the host environment's global object to the sandboxed code.
Remediation
Until the fix is applied, do not expose non-strict host functions to the sandbox. Only inject strict-mode or ES-module functions so a missing this cannot resolve to the host global.
Optional official sources

National CERT insights
?CERT means Computer Emergency Response Team; CSIRT is the closely related term Computer Security Incident Response Team.

Choose official national sources for this report. Each advisory shows its original language. Your selection is remembered on this device and included in shared links.

Official European source

ENISA European Vulnerability Database

Official EUVD identifiers, advisory evidence and known-exploited context. Missing fields are not treated as evidence of low risk.

1 current
ENISA EUVD identifier

EUVD-2026-82898

No EUVD known-exploited evidence

vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.

EUVD state
Present in the current official mapping
Known exploitation
Not present in the current ENISA EUVD known-exploited dataset. This is not proof of no exploitation.
ENISA score
10.0 · CVSS 4.0
Advisory evidence
No linked advisory details stored yet
Recommended actionPatch only the product branches with a verified fix

Critical technical impact with a remotely reachable, unauthenticated path and a public exploit reference; no CISA KEV confirmation is currently recorded. Verified remediation exists for at least one product or source, but 5 structured product or package states remain unresolved. Apply remediation only to the exact product branch confirmed by its source.

Fix availability varies by product
01

What, why and how

vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.

What

vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.

Why

Untrusted data can cross into a code-evaluation path and be interpreted as executable instructions.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

What

vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.

Why

Untrusted data can cross into a code-evaluation path and be interpreted as executable instructions.

How

An attacker operating through a network path may attempt exploitation without authentication or user interaction. If successful, the issue may execute code or commands in the affected security context.

02

Exploit reality and attack path

CVSS severity, EPSS forecast probability, public exploit material and CISA-confirmed exploitation are separate signals.

Observed exploitation
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
No confirmed evidence

No CISA KEV match was present at the last successful refresh. This means no confirmation from that source, not proof of no exploitation.

Public PoC / exploit material
?Confirmed exploitation and public exploit material are separate signals. Attacks can occur without public proof-of-concept or exploit code.
Reference recorded

CISA Vulnrichment records proof-of-concept exploitation in its SSVC data. BlackTree has not independently executed or validated exploit material.

Likely attack path
a network path → Improper Control of Generation of Code ('Code Injection') → execute code or commands in the affected security context
Attack surface
Network
Privileges required
None: unauthenticated exploitation is possible
User interaction
None
Attack complexity
Low: no specialised conditions are recorded
Security boundary
Not a CVSS 4.0 base metric
Weakness
?CWE means Common Weakness Enumeration: a standard category for the underlying weakness.
CWE-94 ↗

CWE-94: Improper Control of Generation of Code ('Code Injection'). The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.

CVSS vector
?CVSS means Common Vulnerability Scoring System. The vector records the metric values used to calculate technical severity.
CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:H/SI:H/SA:H

Common Vulnerability Scoring System 4.0: the compact vector below is decoded into plain language.

AVNetworkAttack vector: The vulnerable component can be reached over a network.ACLowAttack complexity: No specialised conditions are required beyond attacker-controlled input.ATNoneAttack requirements: No additional deployment or execution condition is required.PRNonePrivileges required: The attacker does not need an account or existing privileges.UINoneUser interaction: No action by another user is required.VCHighVulnerable-system confidentiality: A successful attack can cause a major loss.VIHighVulnerable-system integrity: A successful attack can cause a major loss.VAHighVulnerable-system availability: A successful attack can cause a major loss.SCHighSubsequent-system confidentiality: A successful attack can cause a major loss.SIHighSubsequent-system integrity: A successful attack can cause a major loss.SAHighSubsequent-system availability: A successful attack can cause a major loss.
Post-exploitation / living off the land
After compromise, an attacker may use built-in shells, scripting engines, scheduled tasks and native network utilities for discovery, persistence or movement. This is a plausible LoTL path, not evidence that it has occurred for every attack.
NetworkUnauthenticatedRemote code executionCWE-94Public exploit reference
A

Official authority intelligence

Only matched European and national findings are included. Language selectors and unavailable sources are omitted.

ENISA EUVD · EUVD-2026-82898Official EUVD mapping

vm2 through 3.12.0 (fixed in 3.12.1) does not correctly handle a nullish `this` receiver in the apply trap of its bridge (lib/bridge.js): when sandboxed code calls a host-provided non-strict (sloppy-mode) function without a receiver — e.g. `fn()`, a detached method, `fn.call()`, `fn.apply(undefined)`, `Reflect.apply(fn, undefined, [])`, or `fn.bind()()` — the undefined receiver is passed straight through to the host call, and V8 substitutes the host realm's global object for `this`. vm2 then wraps and returns that object to the sandbox, giving sandboxed script a live proxy of the host global. This allows a complete sandbox escape: untrusted script can reach `process` and execute arbitrary code/commands on the host (for example via `process.getBuiltinModule('child_process').execSync`). Exploitation requires that the embedding application expose at least one non-strict host function to the sandbox; strict-mode and ES module host functions are not affected.

Official EUVD record ↗
BSI · German · WID-SEC-2026-3189vm2: Mehrere Schwachstellen ermöglichen Codeausführung

Ein Angreifer kann mehrere Schwachstellen in vm2 ausnutzen, um beliebigen Programmcode auszuführen und um die Integrität zu gefähren.

Official advisory ↗
03

Patch and workaround

Operational remediation based on structured source evidence.

Status
?Patch availability is based on structured fixed-version fields and authoritative update references. If no fix is verified, check the vendor advisory before making a change.
Fix availability varies by product
Affected
Fixed
vm2: 3.12.1
Action
Use the product-specific evidence above. Patch only products with a verified fixed release, and keep every affected or under-investigation state without a matching fix in the remediation queue.
Workaround
Until the fix is applied, do not expose non-strict host functions to the sandbox. Only inject strict-mode or ES-module functions so a missing this cannot resolve to the host global.
04

Evidence and provenance

Published 18 Sept 2026 · Last source change 22 Sept 2026, 14:25 UTC · CWE-94 · Improper Control of Generation of Code ('Code Injection')

CVE recordCVE.org · 5.2
CVSS sourceCNA
EPSS source
?The date BlackTree first stored a score for this CVE from the daily FIRST EPSS feed.
FIRST · tracked since 2026-09-19
European sourceENISA EUVD · EUVD-2026-82898
Product sourceVendor CSAF · Red Hat Product Security
Remediation sourceVendor CSAF · Red Hat Product Security
CWE sourceCNA
NVD statusNVD not scheduled

Core structured fields are present and their contributing authorities are shown above.

Material change intelligence

What changed after publication

View recent updates ↗
  1. Public exploit evidencePublic exploit evidence changed from No public exploit to Public exploit reference.
    Before
    No public exploit
    After
    Public exploit reference
    CVE.org ↗
  2. ENISA EUVD mappingEUVD-2026-82898 was added to the official ENISA EUVD mapping for this CVE.
    Before
    not recorded
    After
    {"euvdId":"EUVD-2026-82898"}
    ENISA EUVD ↗
  3. Catalogue recordCVE added to the BlackTree catalogue.
    CNA ↗
Material fields only · duplicate refreshes suppressed · history retained for the configured operational retention period
Technical terms and abbreviations used in this report
CVE
Common Vulnerabilities and Exposures: the public identifier for one disclosed vulnerability.
CVSS
Common Vulnerability Scoring System: a technical severity framework; it is not patching priority by itself.
EPSS
Exploit Prediction Scoring System: FIRST's estimate of the probability that exploitation activity will be observed in the next 30 days; it is a forecast, not confirmation.
CWE
Common Weakness Enumeration: the standard category describing the underlying software or hardware weakness.
CNA
CVE Numbering Authority: an organisation authorised to assign and publish CVE records.
CISA ADP
Cybersecurity and Infrastructure Security Agency Authorized Data Publisher: structured enrichment added to a CVE record.
NVD
National Vulnerability Database: NIST's enrichment service for CVE records.
CERT / CSIRT
A computer security incident response team that publishes warnings or coordinates incident response.
PoC
Proof of concept: public material that demonstrates or helps reproduce exploitation.
CSAF
Common Security Advisory Framework: a machine-readable format for security advisories.
LoTL
Living off the land: abuse of legitimate tools or system functions during an attack.
Free version - for non-commercial use only.CVE-2026-93603 · cve.blacktree.nl