# CVE-2026-41020: Eaton easyE4 static nonce authentication bypass

Source: https://junglewise.ai/threats/cve-2026-41020-eaton-easye4-uses-a-static-nonce-during-authentication-which  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-10-27. Updated: 2026-10-27  
License: CC BY 4.0 with a link back

CVE-2026-41020 · Severity: high · CVSS 7.5 · Published 2026-10-27

Eaton easyE4 is an industrial automation platform used to control critical infrastructure systems. The platform uses a static nonce value during authentication, which means an attacker who intercepts valid authentication traffic can replay that exchange to gain unauthorized access to the device without needing to know the actual password. This could allow attackers to take control of the affected system.

Technologies: [Eaton easyE4](https://junglewise.ai/threats/technologies/easye4). Vendors: [Eaton](https://junglewise.ai/threats/vendors/eaton).

## Quick answers

**Is CVE-2026-41020 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-41020 being exploited in the wild.

**How severe is CVE-2026-41020?** High severity, with a CVSS score of 7.5, published 27 October 2026.

**Which products and versions are affected?** Eaton easyE4.

**Is there a fix for CVE-2026-41020?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2026-41020 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2026-41020?** Check whether you run Eaton easyE4. 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.

## Technical details

The vulnerability is an authentication bypass due to static nonce reuse in the easyE4 authentication mechanism. An unauthenticated attacker with network access to captured authentication traffic can replay the nonce and authentication exchange to bypass authentication. The fix requires implementing dynamic, non-repeating nonces in the authentication protocol.

## Affected products

- Eaton easyE4

## Timeline

- 2026-10-27: disclosed

## References

- [https://www.eaton.com/content/dam/eaton/company/news-insights/cybersecurity/security-bulletins/eaton-va-2026-1017.pdf](https://www.eaton.com/content/dam/eaton/company/news-insights/cybersecurity/security-bulletins/eaton-va-2026-1017.pdf)

## Related threats

- [Eaton easySoft improper TLS certificate validation](https://junglewise.ai/threats/cve-2026-41022-eaton-easysoft-improperly-validates-tls-certificates-presented-by)
- [Eaton easyE4 weak password policy offline attack](https://junglewise.ai/threats/cve-2026-41021-eaton-easye4-uses-an-insufficiently-strong-password-policy-an)