EUVD-2026-42612
GHSA-75qm-gp28-rcq9
Severity by source
CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:L/VA:N/SC:L/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
Network-reachable API with only default low-privilege access (PR:L); scope changes (S:C) because pollution grants unauthenticated requests privilege, primarily disclosing data (C:H) with minor integrity impact.
Primary rating from Vendor (GitHub_M).
CVSS VectorVendor: GitHub_M
Lifecycle Timeline
2DescriptionCVE.org
n8n is an open source workflow automation platform. Prior to 1.123.61, 2.27.4, and, 2.28.1, an authenticated user with the default workflow:create permission could pollute Object.prototype through a crafted workflow saved, updated, or imported via the workflow API, allowing unauthenticated requests to be treated as a privileged user and exposing user and project listing endpoints. This issue is fixed in versions 1.123.61, 2.27.4, and 2.28.1.
AnalysisAI
Privilege escalation via prototype pollution in n8n workflow automation lets an authenticated low-privilege user (holding the default workflow:create permission) corrupt Object.prototype through a crafted workflow saved, updated, or imported via the workflow API. Once polluted, subsequent unauthenticated requests are evaluated as a privileged user, exposing internal user and project listing endpoints. This is an information-disclosure and access-control flaw with no public exploit identified at time of analysis; CVSS 4.0 base score is 7.1.
Technical ContextAI
n8n is a Node.js/TypeScript open-source workflow automation platform where users build and persist workflow definitions as JSON. The root cause is CWE-1321 (Improperly Controlled Modification of Object Prototype Attributes, i.e. prototype pollution): the workflow persistence/import path merges attacker-controlled JSON keys (such as __proto__) into JavaScript objects without sanitization, mutating the shared Object.prototype. Because n8n's authorization logic reads properties that fall through to the polluted prototype, an unauthenticated request inherits attacker-set properties and is treated as an authenticated privileged principal, unlocking user- and project-listing API endpoints. The single affected package is cpe:2.3:a:n8n-io:n8n across all versions prior to the fixed releases.
RemediationAI
Vendor-released patch: upgrade to n8n 1.123.61, 2.27.4, or 2.28.1 depending on your release line, per advisory GHSA-75qm-gp28-rcq9 (https://github.com/n8n-io/n8n/security/advisories/GHSA-75qm-gp28-rcq9). Until patched, reduce exposure by restricting who holds the default workflow:create permission and limiting workflow save/update/import via the workflow API to trusted operators, since that permission is the required foothold; also place the n8n API behind network access controls so the exposed user and project listing endpoints are not broadly reachable. The trade-off of removing workflow:create from users is a direct loss of core self-service functionality, so treat it as a temporary control and prioritize the upgrade, which fully resolves the prototype-pollution sink.
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External POC / Exploit Code
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