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

> Attackers can steal session tokens from collaborators via malicious resolver registration, leading to unauthorized credential access in n8n.

- **Severity:** High 8.5 (`CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:A/VC:H/VI:H/VA:H/SC:H/SI:L/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 1 Oct 2026
- **Updated:** 1 Oct 2026
- **Also known as:** GHSA-qrhv-fqjc-jcmq, GHSA-rx55-8qhx-4hwx, MINI-ppcv-ppc7-5r33

## What is CVE-2026-103259?

CVE-2026-103259 is a high-severity vulnerability in n8n-io n8n, published on 1 Oct 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.

### Official 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.

Weakness: CWE-863 (Incorrect Authorization)

## Which versions are affected by CVE-2026-103259?


## How do I fix CVE-2026-103259?

Upgrade to a fixed version.

## Is CVE-2026-103259 being exploited?

There is no known exploitation of CVE-2026-103259 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-103259 and fix it if it is affected.

What it is: CVE-2026-103259 is a high-severity vulnerability in n8n-io n8n, published on 1 Oct 2026. An attacker needs administrator access to exploit it, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2026-103259 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-2026-103259/ (Markdown: https://insights.sbomify.com/CVE-2026-103259/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-103259
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-103259
- OSV: https://osv.dev/vulnerability/CVE-2026-103259

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-103259/
Summaries are generated and may contain mistakes; the official description above is the record.