CVE-2026-86078: n8n Denial of Service Vulnerability

MODERATE
Advisory Identifier: GHSA-679f-58pq-4v2c
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CWE-1321
Published
Advisory Summary

CVE-2026-86078 is a MODERATE denial of service vulnerability (CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')) affecting n8n libraries in the npm ecosystem. The issue involves prototype pollution via workflow structure summary can lead to denial of service. Remediation is available by upgrading affected packages to version 2.38.2, 2.37.7.

CVE-2026-86078 at a Glance

CVE Identifier CVE-2026-86078
GHSA Identifier GHSA-679f-58pq-4v2c
Severity MODERATE
CVSS v3.1 Base Score N/A
CWE Classification CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
Affected Product n8n
Package Ecosystem npm
Published Date
Last Updated

How to Fix CVE-2026-86078

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: 2.38.2 
npm install n8n@2.38.2
n8n fixed: 2.37.7 
npm install n8n@2.37.7
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-2026-86078, 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 2.38.2), 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-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution'), where the product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype. 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 The Instance AI workflow summary built its result with get-or-create-then-nested-write idioms keyed by node names and connection keys taken from the stored workflow. Those are arbitrary strings: the restricted-name guard n8n shows in the editor is client-side and is bypassed by posting the workflow to the REST API directly. So a reserved key such as `__proto__` resolved up the prototype chain instead of creating an own key, and the write landed on `Object.prototype` in the main n8n process, affecting every later request. The patch builds the summary with null-prototype accumulators and validates the keys it accepts, so reserved names cannot reach the prototype chain. ## Patches The issue has been fixed in n8n versions 2.37.7 and 2.38.2. Users should upgrade to one of these versions or later to remediate the vulnerability. ## Workarounds If upgrading is not immediately possible, administrators should consider the following temporary mitigations: - Restrict n8n instance access to fully trusted users only. - Remove or leave unconfigured the `N8N_INSTANCE_AI_MODEL*` environment variables to prevent the Instance AI module from reaching the vulnerable code path. - Restart the n8n process to clear any in-memory prototype pollution if an attack is suspected. These workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.

CVE-2026-86078 Affected n8n Versions

2 component(s)
Fixed Versions:
2.38.22.37.7
Product / Package Ecosystem Affected Versions Fixed Version
n8n
npm/n8n
npm
≥ 2.38.0
< 2.38.2
2.38.2
n8n
npm/n8n
npm
< 2.37.7
2.37.7

References

GitHub Advisory / Wiki ADVISORY
https://github.com/n8n-io/n8n/security/advisories/GHSA-679f-58pq-4v2c
NVD — CVE-2026-86078 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-86078
n8n Source Repository REPOSITORY
https://github.com/n8n-io/n8n
n8n Release RELEASE
https://github.com/n8n-io/n8n/releases/tag/n8n@2.37.7
n8n Release RELEASE
https://github.com/n8n-io/n8n/releases/tag/n8n@2.38.2

Frequently Asked Questions

What is CVE-2026-86078?
CVE-2026-86078 is a security vulnerability in n8n involving Prototype Pollution via Workflow Structure Summary Can Lead to Denial of Service under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution').
Which n8n versions are affected?
Affected versions include releases prior to 2.38.2, 2.37.7 across affected packages: n8n.
What version fixes CVE-2026-86078?
Upgrading to 2.38.2, 2.37.7 (or the latest patched release for your respective branch) resolves the vulnerability.
Is n8n affected?
Yes, n8n is affected in releases prior to 2.38.2, 2.37.7. Upgrade your dependency to 2.38.2, 2.37.7 or later.
What CWE is associated with CVE-2026-86078?
CVE-2026-86078 is classified under CWE-1321: Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution') (The product receives input from an upstream component that specifies attributes that are to be initialized or updated in an object, but it does not properly control modifications of attributes of the object prototype.).
How can I check npm dependencies for CVE-2026-86078?
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-679f-58pq-4v2c",
  "modified" : "2026-09-10T21:05:24Z",
  "published" : "2026-09-10T21:05:24Z",
  "aliases" : [ "CVE-2026-86078" ],
  "summary" : "n8n: Prototype Pollution via Workflow Structure Summary Can Lead to Denial of Service",
  "details" : "## Impact\n\nThe Instance AI workflow summary built its result with get-or-create-then-nested-write idioms keyed by node names and connection keys taken from the stored workflow. Those are arbitrary strings: the restricted-name guard n8n shows in the editor is client-side and is bypassed by posting the workflow to the REST API directly. So a reserved key such as `__proto__` resolved up the prototype chain instead of creating an own key, and the write landed on `Object.prototype` in the main n8n process, affecting every later request. The patch builds the summary with null-prototype accumulators and validates the keys it accepts, so reserved names cannot reach the prototype chain.\n\n## Patches\n\nThe issue has been fixed in n8n versions 2.37.7 and 2.38.2. Users should upgrade to one of these versions or later to remediate the vulnerability.\n\n## Workarounds\n\nIf upgrading is not immediately possible, administrators should consider the following temporary mitigations:\n- Restrict n8n instance access to fully trusted users only.\n- Remove or leave unconfigured the `N8N_INSTANCE_AI_MODEL*` environment variables to prevent the Instance AI module from reaching the vulnerable code path.\n- Restart the n8n process to clear any in-memory prototype pollution if an attack is suspected.\n\nThese workarounds do not fully remediate the risk and should only be used as short-term mitigation measures.",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.38.0"
      }, {
        "fixed" : "2.38.2"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "n8n"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "2.37.7"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/n8n-io/n8n/security/advisories/GHSA-679f-58pq-4v2c"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-86078"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/n8n-io/n8n"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/n8n-io/n8n/releases/tag/n8n@2.37.7"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/n8n-io/n8n/releases/tag/n8n@2.38.2"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-1321" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-09-10T21:05:24Z",
    "nvd_published_at" : "2026-09-08T22:19:16Z"
  }
}