CVE-2026-42236: CWE-770: Allocation of Resources Without Limits or Throttling in n8n-io n8n
n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, the MCP OAuth client registration endpoint accepted unauthenticated requests and stored client data without adequate resource controls. An unauthenticated remote attacker could exhaust server memory resources by sending large registration payloads, rendering the n8n instance unavailable. The MCP enable/disable toggle gates MCP access but did not restrict client registrations, meaning the endpoint is reachable regardless of whether MCP access is enabled on the instance. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.
AI Analysis
Technical Summary
The vulnerability in n8n (CVE-2026-42236) involves the MCP OAuth client registration endpoint accepting unauthenticated requests and storing client data without applying resource usage limits or throttling. This allows a remote unauthenticated attacker to send large registration payloads that can exhaust server memory resources, leading to denial of service. The MCP enable/disable toggle does not restrict access to this endpoint, making it reachable regardless of MCP status. The issue affects versions prior to 1.123.32, 2.17.4, and 2.18.1 and has been fixed in these versions.
Potential Impact
An unauthenticated remote attacker can cause a denial of service by exhausting server memory resources through large payload submissions to the client registration endpoint. This can render the affected n8n instance unavailable until resources are restored or the service is restarted.
Mitigation Recommendations
This vulnerability has been patched in n8n versions 1.123.32, 2.17.4, and 2.18.1. Users should upgrade to these or later versions to remediate the issue. No other mitigation or temporary workaround is indicated in the available data.
CVE-2026-42236: CWE-770: Allocation of Resources Without Limits or Throttling in n8n-io n8n
Description
n8n is an open source workflow automation platform. Prior to versions 1.123.32, 2.17.4, and 2.18.1, the MCP OAuth client registration endpoint accepted unauthenticated requests and stored client data without adequate resource controls. An unauthenticated remote attacker could exhaust server memory resources by sending large registration payloads, rendering the n8n instance unavailable. The MCP enable/disable toggle gates MCP access but did not restrict client registrations, meaning the endpoint is reachable regardless of whether MCP access is enabled on the instance. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.
CVSS v4.0
Score 8.7high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
The vulnerability in n8n (CVE-2026-42236) involves the MCP OAuth client registration endpoint accepting unauthenticated requests and storing client data without applying resource usage limits or throttling. This allows a remote unauthenticated attacker to send large registration payloads that can exhaust server memory resources, leading to denial of service. The MCP enable/disable toggle does not restrict access to this endpoint, making it reachable regardless of MCP status. The issue affects versions prior to 1.123.32, 2.17.4, and 2.18.1 and has been fixed in these versions.
Potential Impact
An unauthenticated remote attacker can cause a denial of service by exhausting server memory resources through large payload submissions to the client registration endpoint. This can render the affected n8n instance unavailable until resources are restored or the service is restarted.
Mitigation Recommendations
This vulnerability has been patched in n8n versions 1.123.32, 2.17.4, and 2.18.1. Users should upgrade to these or later versions to remediate the issue. No other mitigation or temporary workaround is indicated in the available data.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-04-25T05:37:12.117Z
- Cvss Version
- 4.0
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 69f8eab1cbff5d8610415b93
Added to database: 5/4/2026, 6:51:29 PM
Last enriched: 5/4/2026, 7:06:19 PM
Last updated: 6/18/2026, 11:40:13 AM
Views: 93
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
External Links
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.