Vulnerability · Published May 4, 2026 · Assigned by GitHub_M

CVE-2026-42235n8n: XSS via MCP OAuth client

High 8.8

In plain English

A high-severity cross-site scripting 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 0.3% (higher than 27% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 4.0)8.8High

Exploit odds (30 days)0.3%top 73.5% 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 versions 1.123.32, 2.17.4, and 2.18.1, an unauthenticated attacker could register a malicious MCP OAuth client with a crafted client_name. If a victim user authorized the OAuth consent dialog and a second user subsequently revoked that access, a toast notification would render the injected script. Clicking the link would execute arbitrary JavaScript in the victim's authenticated n8n browser session, enabling credential and session token theft, workflow manipulation, or privilege escalation. This issue has been patched in versions 1.123.32, 2.17.4, and 2.18.1.

Affected packages & fixed versions

Ecosystem	Package	Fixed in	Advisory
npm	n8n	1.123.32	GHSA-537j-gqpc-p7fq
npm	n8n	2.18.1	GHSA-537j-gqpc-p7fq
npm	n8n	2.17.4	GHSA-537j-gqpc-p7fq

Affected products (as reported)

Vendor	Product	Versions
n8n-io	n8n	< 1.123.32>= 2.17.0, < 2.17.4>= 2.18.0, < 2.18.1

Weakness: CWE-87, CWE-79 · Vector: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:A/VC:H/VI:H/VA:L/SC:H/SI:H/SA:L

References

https://github.com/n8n-io/n8n/security/advisories/GHSA-537j-gqpc-p7fq x_refsource_CONFIRM