# CVE-2026-86076: n8n expression sandbox escape via class-field sanitizer rebinding

Source: https://junglewise.ai/threats/cve-2026-86076-n8n-expression-sandbox-escape-via-class-field-sanitizer-rebinding  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-09-08. Updated: 2026-09-25  
License: CC BY 4.0 with a link back

CVE-2026-86076 · Severity: high · CVSS 8.8 · Published 2026-09-08

n8n is a workflow automation platform that allows users to build and execute automation scripts using expressions. A flaw in the expression compiler's sandbox allows an attacker with expression authoring permissions to execute arbitrary code in the n8n process (on the backend) or in the browser session of any user who opens a malicious workflow (in the editor). An attacker can exploit this by rebinding a class field named `__sanitize` to bypass the security sanitizer and access the Function constructor.

Technologies: [N8n](https://junglewise.ai/threats/technologies/n8n), [n8n (npm)](https://junglewise.ai/threats/technologies/npm-n8n). Vendors: [N8n](https://junglewise.ai/threats/vendors/n8n), [npm](https://junglewise.ai/threats/vendors/npm).

## Quick answers

**Is CVE-2026-86076 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-86076 being exploited in the wild.

**How severe is CVE-2026-86076?** High severity, with a CVSS score of 8.8, published 8 September 2026.

**Which products and versions are affected?** N8n all versions before 1.123.76, versions 2.0.0 to 2.37.6, versions 2.38.0 to 2.38.1; n8n (npm) SEMVER:introduced=0,fixed=1.123.76.

**Is there a fix for CVE-2026-86076?** Yes. n8n (npm): upgrade to 1.123.76 or later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-86076 attacked?** It is attacked over the network, in a web application.

**Am I affected by CVE-2026-86076?** Check whether you run N8n or n8n (npm) at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- n8n (npm): upgrade to 1.123.76 or later

  ```sh
  npm install n8n@1.123.76
  ```


## Technical details

The vulnerability is a code injection flaw (CWE-94) in n8n's expression compiler. The compiler's sanitizer is resolved through a dynamically-scoped `this` context, which allows an attacker to rebind it by creating a class field named `__sanitize`. By rebinding the sanitizer, an attacker can reach the underlying `Function` constructor and execute arbitrary JavaScript code. On the backend, any user with expression authoring permissions can execute code within the n8n process itself; in the editor preview, the malicious expression runs as JavaScript in the session of whoever opens the workflow, potentially compromising other users. The attack requires workflow creation/edit permissions. The fix rejects reserved class-member names. Patches are available in versions 1.123.76, 2.37.7, and 2.38.2.

## Affected products

- n8n n8n all versions before 1.123.76, versions 2.0.0 to 2.37.6, versions 2.38.0 to 2.38.1

## Identifiers

- CVE-2026-86076
- GHSA-hw8v-xxg5-vvvx

## Timeline

- 2026-09-02: disclosed
- 2026-09-10: advisory
- 2026-09-02: patched: patches released for versions 1.123.76, 2.37.7, and 2.38.2

## References

- [https://api.github.com/users/Masofgon](https://api.github.com/users/Masofgon)
- [https://github.com/Masofgon](https://github.com/Masofgon)
- [https://api.github.com/users/Masofgon/gists%7B/gist_id%7D](https://api.github.com/users/Masofgon/gists%7B/gist_id%7D)
- [https://api.github.com/users/Masofgon/repos](https://api.github.com/users/Masofgon/repos)
- [https://avatars.githubusercontent.com/u/68292725?v=4](https://avatars.githubusercontent.com/u/68292725?v=4)
- [https://api.github.com/users/Masofgon/events%7B/privacy%7D](https://api.github.com/users/Masofgon/events%7B/privacy%7D)

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