CVE-2026-77073: n8n before 2.34.1 Cross-Project Credential Access via MCP

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-20 · updated 2026-09-01
Weakness: CWE-639

Description

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.

Affected products

n8n-io n8n: before 2.33.4; 2.34.0 — fixed in 2.33.4

How to fix

Upgrade to a fixed version: n8n-io n8n 2.33.4. Check the vendor advisory for mitigations.

References

https://github.com/n8n-io/n8n/security/advisories/GHSA-vfrj-582q-mvcp
https://www.vulncheck.com/advisories/n8n-before-cross-project-credential-access-via-mcp

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