CVE-2026-103256 n8n before 2.39.6 and 2.40.x before 2.40.1 Credentials Leak via preAuthentication Hook
Attackers with credential update permissions can leak unencrypted passwords to arbitrary hosts by bypassing domain validation in n8n.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-103256?
CVE-2026-103256 is a high-severity vulnerability in n8n-io n8n, published on 1 Oct 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
n8n versions before 2.39.6 and 2.40.0 before 2.40.1 contain a credentials leak vulnerability in the Wekan and Baserow username-and-password credentials that sends unencrypted passwords to unvalidated hosts. Attackers with credential update permissions can modify the host field to receive account passwords at arbitrary hosts, bypassing domain validation controls.
Weakness: CWE-522
Which versions are affected by CVE-2026-103256?
How do I fix CVE-2026-103256?
Upgrade to a fixed version.
Is CVE-2026-103256 being exploited?
There is no known exploitation of CVE-2026-103256 in the wild and no public exploit code.
Sources
Also known as GHSA-6m32-557f-fqq9, GHSA-gx6g-2hm7-c4xf, MINI-j4g7-f48p-h6p9.