CVE-2026-42235: N8n Cross-Site Scripting Vulnerability

HIGH
Advisory Identifier: GHSA-537j-gqpc-p7fq
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CVSS 8.2
CWE-87 CWE-79
Published
Advisory Summary

CVE-2026-42235 is a HIGH (CVSS 8.2) cross-site scripting vulnerability (CWE-87: Improper Neutralization of Alternate XSS Syntax) affecting N8n libraries in the npm ecosystem. The issue involves n8n vulnerable to xss via mcp oauth client. Remediation is available by upgrading affected packages to version 1.123.32, 2.18.1, 2.17.4.

CVE-2026-42235 at a Glance

CVE Identifier CVE-2026-42235
GHSA Identifier GHSA-537j-gqpc-p7fq
Severity HIGH
CVSS v3.1 Base Score 8.2
CWE Classification CWE-87: Improper Neutralization of Alternate XSS Syntax
Affected Product N8n
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 8.2

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:L).

Attack Vector Network (AV:N)
Attack Complexity High (AC:H)
Privileges Required None (PR:N)
User Interaction Required (UI:R)
Scope Changed (S:C)
Confidentiality High (C:H)
Integrity High (I:H)
Availability Low (A:L)

How to Fix CVE-2026-42235

To remediate this vulnerability, upgrade all affected N8n dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

n8n fixed: 1.123.32 
npm install n8n@1.123.32
n8n fixed: 2.18.1 
npm install n8n@2.18.1
n8n fixed: 2.17.4 
npm install n8n@2.17.4
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls n8n

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-42235, inspect your project dependencies using npm:

npm ls n8n

Analyze the terminal output to locate any version of N8n in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 1.123.32), your application is affected.

Note: The npm ls n8n command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-87: Improper Neutralization of Alternate XSS Syntax, where the product does not neutralize or incorrectly neutralizes user-controlled input for alternate script syntax. In N8n, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

## Impact 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. ## Patches This issue has been fixed in n8n version 2.14.2. Users should upgrade to this version or later to remediate the vulnerability. ## Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: - Restrict access to the n8n instance and the MCP OAuth registration endpoint to trusted users only. - Disable MCP server functionality if it is not actively required. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

CVE-2026-42235 Affected N8n Versions

3 component(s)
Fixed Versions:
1.123.322.18.12.17.4
Product / Package Ecosystem Affected Versions Fixed Version
n8n
npm/n8n
npm
< 1.123.32
1.123.32
n8n
npm/n8n
npm
≥ 2.18.0
< 2.18.1
2.18.1
n8n
npm/n8n
npm
≥ 2.17.0
< 2.17.4
2.17.4

References

GitHub Advisory / Wiki ADVISORY
https://github.com/n8n-io/n8n/security/advisories/GHSA-537j-gqpc-p7fq
NVD — CVE-2026-42235 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42235
N8n Source Repository REPOSITORY
https://github.com/n8n-io/n8n

Frequently Asked Questions

What is CVE-2026-42235?
CVE-2026-42235 is a security vulnerability in N8n involving n8n Vulnerable to XSS via MCP OAuth client under CWE-87: Improper Neutralization of Alternate XSS Syntax.
Which N8n versions are affected?
Affected versions include releases prior to 1.123.32, 2.18.1, 2.17.4 across affected packages: n8n.
What version fixes CVE-2026-42235?
Upgrading to 1.123.32, 2.18.1, 2.17.4 (or the latest patched release for your respective branch) resolves the vulnerability.
Is n8n affected?
Yes, n8n is affected in releases prior to 1.123.32, 2.18.1, 2.17.4. Upgrade your dependency to 1.123.32, 2.18.1, 2.17.4 or later.
What is the CVSS score of CVE-2026-42235?
CVE-2026-42235 has a CVSS v3.1 base score of 8.2 (HIGH) with vector string CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:L.
What CWE is associated with CVE-2026-42235?
CVE-2026-42235 is classified under CWE-87: Improper Neutralization of Alternate XSS Syntax (The product does not neutralize or incorrectly neutralizes user-controlled input for alternate script syntax.).
How can I check npm dependencies for CVE-2026-42235?
Run the dependency tree command: 'npm ls n8n'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-537j-gqpc-p7fq",
  "modified" : "2026-05-08T01:31:29Z",
  "published" : "2026-04-29T21:23:04Z",
  "aliases" : [ "CVE-2026-42235" ],
  "summary" : "n8n Vulnerable to XSS via MCP OAuth client",
  "details" : "## Impact\nAn 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.\n\n## Patches\nThis issue has been fixed in n8n version 2.14.2. Users should upgrade to this version or later to remediate the vulnerability.\n\n## Workarounds\nIf upgrading is not immediately possible, administrators should consider the following temporary mitigations:\n- Restrict access to the n8n instance and the MCP OAuth registration endpoint to trusted users only.\n- Disable MCP server functionality if it is not actively required.\n\nThese workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:H/A:L"
  }, {
    "type" : "CVSS_V4",
    "score" : "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"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.123.32"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.18.0"
      }, {
        "fixed" : "2.18.1"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.17.0"
      }, {
        "fixed" : "2.17.4"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/n8n-io/n8n/security/advisories/GHSA-537j-gqpc-p7fq"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42235"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/n8n-io/n8n"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79", "CWE-87" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-04-29T21:23:04Z",
    "nvd_published_at" : "2026-05-04T19:16:06Z"
  }
}