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n8n CVE-2026-77073

| EUVDEUVD-2026-63262 MEDIUM
Authorization Bypass Through User-Controlled Key (CWE-639)
2026-08-20 VulnCheck GHSA-hf5p-745p-2j3h
Authentication Bypass N8n
5.3
CVSS 4.0 · Vendor: VulnCheck
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Severity by source

Vendor (VulnCheck) PRIMARY
5.3 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/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
5.0 MEDIUM

Network attack by low-privilege MCP key holder; scope change applies as impact crosses project boundaries; no confidentiality loss, only unauthorized integrity write.

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

Primary rating from Vendor (VulnCheck).

CVSS VectorVendor: VulnCheck

CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:L/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
Low
Privileges Required
Low
User Interaction
None
Scope
X

Lifecycle Timeline

2
Patch available
Aug 20, 2026 - 12:16 EUVD
Analysis Generated
Aug 20, 2026 - 12:14 vuln.today

DescriptionCVE.org

n8n versions before 2.34.1 contain a credential validation bypass in the MCP create_workflow_from_code tool when authentication type is set to an expression. Attackers with a valid MCP Bearer API key and knowledge of a target credential ID can persist unauthorized cross-project credential references on workflows in different projects.

AnalysisAI

Cross-project credential reference injection in n8n before 2.34.1 allows low-privileged attackers holding a valid MCP Bearer API key to bypass authorization controls in the create_workflow_from_code MCP tool and embed references to credentials belonging to other projects into workflows they should not control. The bypass is conditional on the credential authentication type being set to 'expression', at which point n8n fails to enforce project-scoped authorization on credential objects. …

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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata

Access
Obtain valid MCP Bearer API key
Delivery
Enumerate target credential ID across project boundary
Exploit
Craft create_workflow_from_code request with expression auth type
Execution
Bypass credential project-scope validation
Persist
Persist unauthorized credential reference in victim project workflow
Impact
Trigger workflow execution using stolen credential reference
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Vulnerability AssessmentAI

Exploitation Exploitation requires: (1) a valid MCP Bearer API key for the n8n instance, establishing a low-privilege authenticated foothold; (2) knowledge or enumeration of a target credential ID belonging to a different project; (3) the target credential must be configured with authentication type set to 'expression' - this is the specific configuration state that triggers the validation bypass; and (4) the n8n MCP server interface must be reachable over the network. … Additional conditions and limiting factors are described in the full assessment.
Risk Assessment The CVSS 4.0 vector (AV:N/AC:L/AT:N/PR:L/UI:N) with scores across VC:N/VI:L/VA:N/SC:N/SI:L/SA:N accurately captures the impact: low-complexity network exploitation by a low-privilege attacker, with integrity effects limited to unauthorized reference persistence rather than direct credential exfiltration. … Full risk analysis with EPSS, KEV, and SSVC signal comparison available after sign-in.
Exploit Scenario An attacker operating in a shared n8n instance obtains a valid MCP Bearer API key - either legitimately through a low-privilege account or via a compromised key. They enumerate or guess a credential ID belonging to a different project, then call the create_workflow_from_code MCP tool with a workflow definition that references that credential under an 'expression' authentication type. …
Remediation Upgrade to n8n version 2.34.1 or later, which resolves the credential validation bypass per the vendor advisory at https://github.com/n8n-io/n8n/security/advisories/GHSA-vfrj-582q-mvcp. … Detailed patch versions, workarounds, and compensating controls in full report.
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CVE-2026-77073 vulnerability details – vuln.today
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