# CVE-2026-120976: Arista EOS sensitive data exposure in diagnostic logs during SSU

Source: https://junglewise.ai/threats/cve-2026-120976-on-affected-platforms-running-arista-eos-with-ieee-802-1x  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-10. Updated: 2026-11-10  
License: CC BY 4.0 with a link back

CVE-2026-120976 · Severity: medium · CVSS 6 · Published 2026-11-10

Arista EOS switches running IEEE 802.1X authentication with MACsec can leak sensitive authentication keys in diagnostic data when reloading during a Smart Switch Upgrade. An attacker with administrative access to the device could recover these keys and compromise the confidentiality and integrity of network traffic protected by MACsec. The vulnerability only occurs when an active 802.1X session is present during the SSU reload.

Technologies: [Arista Eos](https://junglewise.ai/threats/technologies/eos). Vendors: [Arista](https://junglewise.ai/threats/vendors/arista).

## Quick answers

**Is CVE-2026-120976 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-120976 being exploited in the wild.

**How severe is CVE-2026-120976?** Medium severity, with a CVSS score of 6, published 10 November 2026.

**Which products and versions are affected?** Arista Eos 4.36.2F and below (4.36.x); 4.35.6M and below (4.35.x); 4.34.8M and below (4.34.x); 4.33.9M and below (4.33.x); all 4.32.x; 4.22.0F-4.31 (EOL).

**Is there a fix for CVE-2026-120976?** Yes: fixed in EOS 4.37.0F and later, 4.36.3M and later, 4.35.7M and later, 4.34.9M and later, 4.33.10M and later. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-120976 attacked?** It is attacked with local access, in a network appliance.

**Am I affected by CVE-2026-120976?** Check whether you run Arista Eos 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

- Fixed in EOS 4.37.0F and later, 4.36.3M and later, 4.35.7M and later, 4.34.9M and later, 4.33.10M and later

## Technical details

CWE-532: Insertion of Sensitive Information into Log File. When EOS devices with IEEE 802.1X authentication and MACsec using dot1x-derived keys reload during SSU, sensitive authentication material is recorded in diagnostic data. An attacker with administrative (high privilege) access to the device can extract these keys from the diagnostic logs, requiring only local access to the device itself and an active 802.1X/MACsec session during the reload.

## Affected products

- Arista EOS 4.36.2F and below (4.36.x); 4.35.6M and below (4.35.x); 4.34.8M and below (4.34.x); 4.33.9M and below (4.33.x); all 4.32.x; 4.22.0F-4.31 (EOL)

## Timeline

- 2026-11-10: disclosed

## References

- [https://www.arista.com/en/support/advisories-notices/security-advisory/25038-security-advisory-0216](https://www.arista.com/en/support/advisories-notices/security-advisory/25038-security-advisory-0216)

## Related threats

- [Arista EOS path traversal in eAPI service](https://junglewise.ai/threats/cve-2026-121371-on-affected-eos-versions-with-the-eapi-service-enabled-a)
- [Arista EOS denial of service in PTP](https://junglewise.ai/threats/cve-2026-121370-on-affected-platforms-running-arista-eos-with-precision-time)
- [Arista EOS denial of service via resource exhaustion](https://junglewise.ai/threats/cve-2026-121369-on-affected-platforms-running-arista-eos-under-specific-link)
- [Arista EOS BFD authentication out-of-bounds write](https://junglewise.ai/threats/cve-2026-121368-on-affected-platforms-running-arista-eos-with-bidirectional)
- [Arista EOS RIPv2 silent enablement on management interfaces](https://junglewise.ai/threats/cve-2026-121367-on-affected-arista-eos-platforms-with-routing-information)