Vulnerability · Published Sep 8, 2026 · Assigned by GitHub_M

CVE-2026-86078n8n: Prototype Pollution via Workflow Structure Summary Can Lead to Denial of Service

Medium 6.0

In plain English

A medium-severity prototype pollution in n8n from n8n-io. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.6% (higher than 48% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)6.0Medium

Exploit odds (30 days)0.6%top 51.8% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack toolingNoneno public tooling known

Official description

n8n is an open source workflow automation platform. Prior to 2.37.7 and 2.38.2, the Instance AI workflow summary used node names and connection keys from stored workflows as ordinary object keys. A workflow submitted through the REST API could contain __proto__ or constructor, causing nested writes to reach Object.prototype in the main n8n process and disrupt later requests. The affected function is summarizeWorkflowStructure in packages/@n8n/instance-ai/src/tools/workflows/summarize-workflow.ts. This issue is fixed in versions 2.37.7 and 2.38.2.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	n8n	2.38.2	GHSA-679f-58pq-4v2c
npm	n8n	2.37.7	GHSA-679f-58pq-4v2c

Affected products (as reported)

Vendor	Product	Versions
n8n-io	n8n	< 2.37.7>= 2.38.0, < 2.38.2

Weakness: CWE-1321 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

References

https://github.com/n8n-io/n8n/security/advisories/GHSA-679f-58pq-4v2c x_refsource_CONFIRM
https://github.com/n8n-io/n8n/releases/tag/n8n@2.37.7 x_refsource_MISC
https://github.com/n8n-io/n8n/releases/tag/n8n@2.38.2 x_refsource_MISC