CVE-2026-110842

n8n before 2.41.4 and 2.42.1 Prototype Pollution via MCP Workflow-Validation Interpreter

State: Published
Severity: 7.7 High
Published: Oct 14, 2026
Updated: Oct 15, 2026
Reserved: Oct 14, 2026

Description

n8n before 2.41.4 and 2.42.x before 2.42.1 contains a prototype pollution vulnerability in the MCP workflow-validation tool, whose interpreter evaluates caller-supplied code in the main process, reads inherited properties, and permits assignment onto shared prototypes. An authenticated member holding only a workflow:read grant can replace a built-in method with one returning a truthy value so server-side permission checks accept unheld scopes, enabling takeover of owner accounts not protected by MFA.

Scores

CVSS	Score	Vector	Source
4.0	7.7 High	CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N	VulnCheck

Weaknesses

CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')

Affected Products

Product	Versions
n8nn8n-io	before 2.41.4Affected 2.42.0 to before 2.42.1Affected

References

GitHub Security Advisory (GHSA-5jr4-xmvf-frmj)vendor-advisory
VulnCheck Advisory: n8n before 2.41.4 and 2.42.1 Prototype Pollution via MCP Workflow-Validation Interpreterthird-party-advisory

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