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n8n EUVDEUVD-2026-63271

| CVE-2026-77083 MEDIUM
Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution) (CWE-1321)
2026-08-20 VulnCheck GHSA-2664-hr5v-554w
Information Disclosure Prototype Pollution N8n
6.0
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
6.0 MEDIUM
CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
vuln.today AI
7.1 HIGH

Network vector via authenticated workflow execution; high complexity from allowlist dependency; PR:L for workflow authors; scope change as escape reaches host process.

3.1 AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:L/A:N
4.0 AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:H/SI:L/SA:N

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:H/AT:P/PR:L/UI:N/VC:H/VI:L/VA:N/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Attack Vector
Network
Attack Complexity
High
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

2
Patch available
Aug 20, 2026 - 12:16 EUVD
Analysis Generated
Aug 20, 2026 - 12:06 vuln.today

DescriptionCVE.org

n8n is a workflow automation platform. In versions prior to 1.123.69, 2.33.4, and 2.34.1, the JavaScript Code node's VM sandbox did not freeze the sandbox's Function.prototype, allowing an authenticated user with the ability to create and execute workflows to pollute it from within a Code node execution and recover a reference to the host's globalThis, resulting in a sandbox escape. The full exploit chain additionally depends on specific modules being available as allowlisted imports in the deployment's configuration. The issue is fixed in versions 1.123.69, 2.33.4, and 2.34.1.

AnalysisAI

Sandbox escape in n8n's JavaScript Code node allows authenticated workflow authors to break out of the Node.js VM sandbox by polluting an unfrozen Function.prototype, ultimately recovering a reference to the host process's globalThis object. Affected are n8n deployments running versions prior to 1.123.69, 2.33.4, and 2.34.1 where users hold workflow creation and execution permissions. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Authenticate as low-privileged n8n user
Delivery
Create workflow with malicious Code node
Exploit
Pollute Function.prototype inside VM sandbox
Execution
Recover reference to host globalThis
Persist
Leverage allowlisted Node.js modules
Impact
Exfiltrate secrets or execute host-level commands
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Vulnerability AssessmentAI

Exploitation Exploitation requires an authenticated account with permissions to create and execute n8n workflows containing JavaScript Code nodes - this is a low-privilege but non-anonymous condition (PR:L in CVSS 4.0). … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 base score of 6.0 accurately reflects a nuanced risk profile. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An authenticated n8n user with workflow authoring rights creates a Code node containing JavaScript that modifies Function.prototype within the VM sandbox context. Because the sandbox does not freeze this prototype, the modification persists and provides a path to reference the host Node.js process's globalThis object, escaping the sandbox isolation boundary. …
Remediation Vendor-released patches are available: upgrade to n8n version 1.123.69, 2.33.4, or 2.34.1 depending on the active release branch. … Detailed patch versions, workarounds, and compensating controls in full report.
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Same weakness CWE-1321 – Improperly Controlled Modification of Object Prototype Attributes (Prototype Pollution)

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Same technique Information Disclosure

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EUVD-2026-63271 vulnerability details – vuln.today
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