CVE-2026-103259: n8n before 2.39.6 and 2.40.x before 2.40.1 Session Token Leak via Dynamic Credentials

Severity: high (CVSS 7.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-10-01 · updated 2026-10-01
Weakness: CWE-863

Description

n8n versions before 2.39.6 and 2.40.0 before 2.40.1 contain a session token leakage vulnerability in the Dynamic Credentials authorize and revoke endpoints. Attackers with resolver registration capability can capture collaborators' session tokens by setting a fallback resolver to an attacker-controlled endpoint during the account connection flow, enabling unauthorized credential access.

Affected products

n8n-io n8n: before 2.39.6; from 2.40.0 before 2.40.1 — fixed in 2.39.6, 2.40.1

How to fix

Upgrade to a fixed version: n8n-io n8n 2.39.6, 2.40.1. Check the vendor advisory for mitigations.

References

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