How severe is CVE-2026-42236?

CVE-2026-42236 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-42236 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-42236?

CVE-2026-42236 primarily affects N8n. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2026-42236?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

Does CVE-2026-42236 have an EU (EUVD) identifier?

Yes. CVE-2026-42236 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27111.

When was CVE-2026-42236 published?

CVE-2026-42236 was published on 2026-05-04 and last updated on 2026-06-17.

CVE-2026-42236

CVE-2026-42236 is a high-severity vulnerability in N8n with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-770.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.7
EPSS exploit prediction: 0% (38th percentile)
Actively exploited: Not listed in CISA KEV
EU (EUVD) id: EUVD-2026-27111
Weakness: CWE-770
Affected product: N8n
Published: 2026-05-04
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2026-42236?: 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.
How severe is CVE-2026-42236?: CVE-2026-42236 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-42236 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (38th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-42236?: CVE-2026-42236 primarily affects N8n. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2026-42236?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
Does CVE-2026-42236 have an EU (EUVD) identifier?: Yes. CVE-2026-42236 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2026-27111.
When was CVE-2026-42236 published?: CVE-2026-42236 was published on 2026-05-04 and last updated on 2026-06-17.

References

https://github.com/n8n-io/n8n/security/advisories/GHSA-49m9-pgww-9vq6

Affected products (2)

cpe:2.3:a:n8n:n8n:*:*:*:*:enterprise:node.js:*:*
cpe:2.3:a:n8n:n8n:2.18.0:*:*:*:enterprise:node.js:*:*

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