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.
CVE-2026-42235
This critical-severity CVE scores 9.6 under NVD CVSS v3. EPSS exploit probability: 0.1%, top 70% of all CVEs by exploit prediction. GitHub Security Advisory data not yet ingested — confidence will rise once GHSA publishes (typical lag: hours to days for open-source ecosystem CVEs; never for infrastructure-only CVEs).
- High severity, but no confirmed exploitation yet
No vendor fix yet — apply a workaround or compensating control (WAF / firewall / segmentation) and watch for a patch.
- CVSS v3
- 9.6
- EG Score
- 9.6(medium)
- EPSS
- 25.6%
- KEV
- Not listed
Published
May 4, 2026
Last Modified
May 6, 2026
Advisory Details (1)
Auto-updated May 4, 2026XSS via MCP OAuth client · Advisory · n8n-io/n8n · GitHub
https://github.com/n8n-io/n8n/security/advisories/GHSA-537j-gqpc-p7fqAffected Packages
(1 across 1 ecosystem)
npm(1)
| Package | Vulnerable range | Fixed in | Dependents |
|---|---|---|---|
| n8n | — | 2.17.4 | — |
Weakness Classification(2)
MITRE Common Weakness Enumeration — the root-cause categories this CVE belongs to.
Data Freshness Timeline
(refreshed 8× in last 7d / 33× in last 30d)
Each row is a source pipeline that fetched or updated this CVE on that date, with what changed. For example, "NVD update" means NVD published or revised its analysis for this CVE; "MITRE cvelistV5" means we ingested or refreshed it from the CNA feed. Most recent first.
- 2026-07-22 14:08 UTCEPSS rescore
- 2026-07-21 15:24 UTCEPSS rescore
- 2026-07-20 18:02 UTCOSV refresh
- 2026-07-20 17:08 UTCEPSS rescore
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- 2026-06-29 14:06 UTCEPSS rescore
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- 2026-06-06 13:47 UTCEPSS rescore
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- 2026-05-31 00:16 UTCEPSS rescore
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- 2026-05-29 13:44 UTCEPSS rescore
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- 2026-05-28 13:44 UTCEPSS rescore
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- 2026-05-27 13:40 UTCEPSS rescore
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- 2026-05-26 13:44 UTCEPSS rescore
- 2026-05-26 07:18 UTCEPSS rescore
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- 2026-05-20 22:38 UTCEPSS rescore
- 2026-05-20 22:38 UTCEPSS rescore
- 2026-05-20 14:34 UTCEG score recompute
- 2026-05-20 11:22 UTCEPSS rescore
- 2026-05-20 11:22 UTCEPSS rescore
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Frequently asked(5)
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Dependency Blast Radius
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