GHSA-679f-58pq-4v2c CVE-2026-86078
n8n: Prototype Pollution via Workflow Structure Summary Can Lead to Denial of Service
- Severity
- 0.0 / 10
- Medium · CVSS 4.0
- Exploit chance (EPSS)
- 0.59%
- Chance of exploitation in the next 30 days. Higher than 48.01% of scored vulnerabilities.
- Known exploited
- No
- Not in CISA's catalog
- Weakness
- CWE-1321 Improperly Controlled Modification of Object Prototype Attributes ('Prototype Pollution')
- Fix
2.38.2- Upgrade n8n to this version or later
Description
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.
Affected versions
npm
How to fix
Move to the fixed version or later with your package manager, update the lockfile, and run your tests. If the package only arrives through another dependency, upgrade that dependency first. If none of its releases pulls a fixed version yet, force the version with your package manager's override.
n8n npm → 2.38.2
- npm
npm install n8n@2.38.2- yarn
yarn add n8n@2.38.2- pnpm
pnpm add n8n@2.38.2
Severity breakdown
CVSS 4.0 0.0
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
- Attack vector
- Network
- Attack complexity
- Low
- Attack requirements
- Present
- Privileges required
- Low
- User interaction
- None
- Confidentiality (vulnerable system)
- None
- Integrity (vulnerable system)
- None
- Availability (vulnerable system)
- High
- Confidentiality (subsequent systems)
- None
- Integrity (subsequent systems)
- None
- Availability (subsequent systems)
- None
CVSS 3.1 6.5
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
- Attack vector
- Network
- Attack complexity
- Low
- Privileges required
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- None
- Integrity
- None
- Availability
- High
Weakness
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 to prevent it
- Implementation: By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- Architecture and Design: By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- Implementation: When handling untrusted objects, validating using a schema can be used.
- Implementation: By using an object without prototypes (via Object.create(null) ), adding object prototype attributes by accessing the prototype via the special attributes becomes impossible, mitigating this weakness.
- Implementation: Map can be used instead of objects in most cases. If Map methods are used instead of object attributes, it is not possible to access the object prototype or modify it.
References
Advisories
Packages
Other links
Timeline
- Published
- Last updated by the source
- Latest EPSS score
Related advisories
| Advisory | Severity | Why it's related |
|---|---|---|
| GHSA-v98v-ff95-f3cp n8n Vulnerable to Remote Code Execution via Expression Injection | High Known exploited | Also affects n8n |
| GHSA-qgpw-8g46-w95v n8n: Git Node branch.<name>.remote Config Key Bypasses Sandbox Path Restriction, Enabling Local Git Repository Read | Medium | Also affects n8n |
| GHSA-65xw-2v52-jhxc n8n: Cross-User Active Workflow ID and Lifecycle Event Disclosure via Missing userId Filter | Medium | Also affects n8n |
| GHSA-pq6c-vh67-xpm3 n8n: Log Streaming Event Destinations Decrypt Generic-Auth Credentials Without Ownership Check | Medium | Also affects n8n |
| GHSA-cqr2-h44g-v75v n8n: Cross-Tenant Project-Member PII Disclosure via Missing Per-Project Scope Check on Role Assignment Endpoints | Medium | Also affects n8n |
| GHSA-pf83-w3f9-8m37 n8n: Disabled OIDC SSO Endpoints Remain Active and Issue Valid Sessions | Medium | Also affects n8n |
| GHSA-6xcw-7xm6-48c6 n8n: Expression Sandbox Escape via Shared Builtin Tampering and Code-Printer Injection Leads to Code Execution | High | Also affects n8n |
| GHSA-34ff-336r-5q23 n8n: Domain-Restriction Bypass via Unguarded Model-Search Endpoint in OpenAI Chat Model Node | Medium | Also affects n8n |
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