Auth bypass in N8n-Io N8n
CVE-2026-103259
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.
Vulnerability class: Broken Access Control
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.6 (High). Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:C/C:H/I:H/A:H.
EPSS exploit prediction
No EPSS score from FIRST.org yet. New CVEs usually get one within a few days; no score means no signal yet, not low risk. How EPSS works.
Affected products
Weakness classification (CWE)
References
- github.com/n8n-io/n8n/security/advisories/GHSA-rx55-8qhx-4hwx (vendor-advisory)
- www.vulncheck.com/advisories/n8n-before-2.39.6-and-2.40-x-before-2.40.1-session… (third-party-advisory)
Frequently asked questions
- What is CVE-2026-103259?
- CVE-2026-103259 is a high-severity vulnerability in N8n-Io N8n, classified under Incorrect Authorization. CVSS score: 7.6/10. Published 2026-10-01.
- How severe is CVE-2026-103259?
- High severity. CVSS v3 base score is 7.6 out of 10.