CVE-2026-86078: n8n prototype pollution in workflow summary

CVE-2026-86078 · Severity: medium · CVSS 6.5 · Published 2026-09-08

n8n is an open-source workflow automation platform. A flaw in the Instance AI workflow summary feature allows authenticated users to modify object prototypes via specially crafted API requests, disrupting service availability for all users. While exploitation requires a valid n8n account, the vulnerability impacts all subsequent operations on the server.

Technologies: N8n, n8n (npm). Vendors: N8n, npm.

Quick answers

Is CVE-2026-86078 exploited in the wild?
No. Junglewise Threat Intelligence has no report of CVE-2026-86078 being exploited in the wild.
How severe is CVE-2026-86078?
Medium severity, with a CVSS score of 6.5, published 8 September 2026.
Which products and versions are affected?
N8n < 2.37.7 and >= 2.38.0, < 2.38.2; n8n (npm) SEMVER:introduced=2.38.0,fixed=2.38.2.
Is there a fix for CVE-2026-86078?
Yes. n8n (npm): upgrade to 2.38.2 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
How is CVE-2026-86078 attacked?
It is attacked over the network, in a web application.
Am I affected by CVE-2026-86078?
Check whether you run N8n or n8n (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

How to fix

  • n8n (npm): upgrade to 2.38.2 or later
    npm install n8n@2.38.2

Technical details

This is a prototype pollution vulnerability (CWE-1321) in n8n's Instance AI workflow summary builder. The vulnerable code constructs summary objects using node names and connection keys taken directly from stored workflows via get-or-create-then-nested-write patterns. Although the web editor enforces client-side restrictions on key names, an attacker with valid credentials can bypass this by posting directly to the REST API with reserved property names such as `__proto__`, `constructor`, or `prototype`. When these keys are used as object property names without validation, they resolve up the prototype chain rather than creating own properties, causing writes to land on Object.prototype in the main n8n process. This pollution persists in memory and affects every subsequent request. The fix validates key names and uses null-prototype accumulators (Object.create(null)) to prevent prototype chain pollution. Patches are available in versions 2.37.7 and 2.38.2 or later.

Affected products

  • n8n n8n < 2.37.7 and >= 2.38.0, < 2.38.2

Identifiers

  • CVE-2026-86078
  • GHSA-679f-58pq-4v2c

Timeline

  • 2026-09-02: disclosed: Vulnerability published to GitHub Advisory Database
  • 2026-09-10: patched: Patches released in n8n 2.37.7 and 2.38.2

References

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