CVE-2026-42236
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.
AI Insight
LLM-synthesized narrative grounded in this CVE's description and references.
Affected packages
Versions sourced from the GitHub Security Advisory.
| Package | Affected versions | Patched versions |
|---|---|---|
n8nnpm | < 1.123.32 | 1.123.32 |
n8nnpm | >= 2.18.0, < 2.18.1 | 2.18.1 |
n8nnpm | >= 2.0.0, < 2.17.4 | 2.17.4 |
Affected products
2Patches
Vulnerability mechanics
References
3- github.com/advisories/GHSA-49m9-pgww-9vq6ghsaADVISORY
- github.com/n8n-io/n8n/security/advisories/GHSA-49m9-pgww-9vq6nvdVendor AdvisoryWEB
- nvd.nist.gov/vuln/detail/CVE-2026-42236ghsaADVISORY
News mentions
1- ⚡ Weekly Recap: Exchange 0-Day, npm Worm, Fake AI Repo, Cisco Exploit and MoreThe Hacker News · May 18, 2026