Summary
n8n: Prototype Pollution via Workflow Structure Summary Can Lead to Denial of Service
Workarounds
If upgrading is not immediately possible, administrators should consider the following temporary mitigations:
- Restrict n8n instance access to fully trusted users only.
- Remove or leave unconfigured the
N8N_INSTANCE_AI_MODEL*environment variables to prevent the Instance AI module from reaching the vulnerable code path. - Restart the n8n process to clear any in-memory prototype pollution if an attack is suspected.
These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.
Impact
The Instance AI workflow summary built its result with get-or-create-then-nested-write idioms keyed by node names and connection keys taken from the stored workflow. Those are arbitrary strings: the restricted-name guard n8n shows in the editor is client-side and is bypassed by posting the workflow to the REST API directly. So a reserved key such as __proto__ resolved up the prototype chain instead of creating an own key, and the write landed on Object.prototype in the main n8n process, affecting every later request. The patch builds the summary with null-prototype accumulators and validates the keys it accepts, so reserved names cannot reach the prototype chain.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
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The issue has been fixed in n8n versions 2.37.7 and 2.38.2. Users should upgrade to one of these versions or later to remediate the vulnerability.
Frequently Asked Questions
- What is CVE-2026-86078? CVE-2026-86078 is a medium-severity security vulnerability in n8n (npm), affecting versions >= 2.38.0, < 2.38.2. It is fixed in 2.38.2, 2.37.7.
- Which versions of n8n are affected by CVE-2026-86078? n8n (npm) versions >= 2.38.0, < 2.38.2 is affected.
- Is there a fix for CVE-2026-86078? Yes. CVE-2026-86078 is fixed in 2.38.2, 2.37.7. Upgrade to this version or later.
- Is CVE-2026-86078 exploitable, and should I be worried? Whether CVE-2026-86078 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2026-86078 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2026-86078?
- Upgrade
n8nto 2.38.2 or later - Upgrade
n8nto 2.37.7 or later
- Upgrade