n8n: Improperly Controlled Modification of Object Prototype Attributes
CVE-2026-44789 is a critical-severity improperly controlled modification of object prototype attributes vulnerability in n8n, with a CVSS 3.1 base score of 9.9 out of 10. It can be exploited remotely over the network by an attacker with a low-privileged account, without any action from a user. Affected n8n versions: < 1.123.43; >= 2.0.0-rc.0, < 2.20.7; >= 2.21.0, < 2.21.1. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.53% chance of exploitation within 30 days, which is low compared with other CVEs.
Critical severity: a successful attack would have severe impact.
What to do
- Check which version of n8n you run against the affected versions below, and install the vendor's latest release.
- Read the advisory on github.com for workarounds and exact fixed builds.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| n8n | n8n | < 1.123.43; >= 2.0.0-rc.0, < 2.20.7; >= 2.21.0, < 2.21.1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- LowA basic user account is enough.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 4.0 | 9.4 | Critical | CNA (github.com) |
| CVSS 3.1 | 9.9 | Critical | NVD |
Official description
n8n is an open source workflow automation platform. Prior to 1.123.43, 2.22.1, and 2.20.7, an authenticated user with permission to create or modify workflows could achieve global prototype pollution via an unvalidated pagination parameter in the HTTP Request node. Combined with other techniques this could lead to RCE on the instance. This vulnerability is fixed in 1.123.43, 2.22.1, and 2.20.7.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improperly Controlled Modification of Object Prototype Attributes
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 developers prevent this class of flaw
- By freezing the object prototype first (for example, Object.freeze(Object.prototype)), modification of the prototype becomes impossible.
- By blocking modifications of attributes that resolve to object prototype, such as proto or prototype, this weakness can be mitigated.
- When handling untrusted objects, validating using a schema can be used.
More Improperly Controlled Modification of Object Prototype Attributes vulnerabilities (CWE-1321)
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Advisories
Other vulnerabilities in n8n
- 7.5 High severity
- 7.7 High severity
- 8.2 High severity
- 8.8 High severity
- 7.5 High severity
- 7.1 High severity
Recent Improperly Controlled Modification of Object Prototype Attributes vulnerabilities
- 9.9 Critical severity
- 8.5 High severity
- 9.9 Critical severity
- 8.6 High severity
- 9.1 Critical severity
- 9.1 Critical severity
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