# 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.

- **Severity:** High 7.1 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:H/VI:N/VA:N/SC:H/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 1 Oct 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-6m32-557f-fqq9, GHSA-gx6g-2hm7-c4xf, MINI-j4g7-f48p-h6p9

## 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 (Insufficiently Protected Credentials)

## 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.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103256 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-103256 in the wild and no public exploit code.

Affected product: n8n-io n8n. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-103256/ (Markdown: https://insights.sbomify.com/CVE-2026-103256/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103256
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103256
- OSV: https://osv.dev/vulnerability/CVE-2026-103256

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103256/
Summaries are generated and may contain mistakes; the official description above is the record.