CVE-2026-86078: CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') in n8n-io n8n
Description
CVE-2026-86078 is a prototype pollution vulnerability in the n8n workflow automation platform. Prior to versions 2.37.7 and 2.38.2, the Instance AI workflow summary function improperly used node names and connection keys from stored workflows as object keys, allowing crafted workflows submitted via the REST API to modify Object.prototype. This could disrupt subsequent requests in the main n8n process. The vulnerability is fixed in versions 2.37.7 and 2.38.2.
CVSS v4.0
Score 6.0medium
Affected software
n8n-io
n8n
pkg:github/n8n-io/n8nRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability exists in the summarizeWorkflowStructure function of n8n's Instance AI workflow summary feature. It improperly handles node names and connection keys from stored workflows by using them as ordinary object keys without sanitization. An attacker submitting a workflow containing keys like __proto__ or constructor via the REST API can cause nested writes to Object.prototype, leading to prototype pollution. This can disrupt the behavior of the main n8n process for later requests. The issue is resolved in n8n versions 2.37.7 and 2.38.2.
Potential Impact
Successful exploitation allows an attacker with permission to submit workflows via the REST API to perform prototype pollution on the main n8n process. This can disrupt the processing of subsequent requests, potentially causing denial of service or unexpected behavior. There is no indication of remote code execution or data disclosure from the provided data.
Mitigation Recommendations
Upgrade n8n to version 2.37.7 or later, or 2.38.2 or later, where this vulnerability is fixed. No other mitigation steps are indicated in the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-09-04T19:34:03.100Z
- Cvss Version
- 4.0
- State
- PUBLISHED
Threat ID: 6aa08023acd9273b4940c39a
Added to database: 09/08/2026, 21:37:39 UTC
Last enriched: 09/16/2026, 02:28:22 UTC
Last updated: 10/11/2026, 18:48:23 UTC
Views: 75
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