Arista EOS up to 4.36.2F MACsec information disclosure

Summaryinfo

A vulnerability was found in Arista EOS up to 4.36.2F. It has been classified as problematic. This vulnerability affects unknown code of the component MACsec. This manipulation causes information disclosure. This vulnerability is registered as CVE-2026-120976. The attack needs to be launched locally. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability was found in Arista EOS up to 4.36.2F. It has been declared as problematic. Affected by this vulnerability is an unknown code block of the component MACsec. The manipulation with an unknown input leads to a information disclosure vulnerability. The CWE definition for the vulnerability is CWE-200. The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information. As an impact it is known to affect confidentiality. The summary by CVE is:

On affected platforms running Arista EOS with IEEE 802.1X authentication and MACsec using dynamically derived keys, sensitive authentication information may be recorded in diagnostic data during a Smart Switch Upgrade (SSU). An attacker with administrative access on the device who obtains the affected diagnostic data could recover sensitive authentication information. This could potentially compromise the confidentiality and integrity of traffic protected by MACsec on the affected link. The vulnerability is only exposed during and after an SSU reload where an active 802.1X session used for MACsec is present.

It is possible to read the advisory at arista.com. This vulnerability is known as CVE-2026-120976 since 11/03/2026. The exploitation appears to be easy. Attacking locally is a requirement. The exploitation requires an enhanced level of successful authentication. The technical details are unknown and an exploit is not publicly available. The attack technique deployed by this issue is T1592 according to MITRE ATT&CK.

Upgrading to version 4.32.0F or 4.33.0F eliminates this vulnerability.

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Productinfo

Vendor

• Arista

Name

• EOS

Version

• 4.0
• 4.1
• 4.2
• 4.3
• 4.4
• 4.5
• 4.6
• 4.7
• 4.8
• 4.9
• 4.10
• 4.11
• 4.12
• 4.13
• 4.14
• 4.15
• 4.16
• 4.17
• 4.18
• 4.19
• 4.20
• 4.21
• 4.22
• 4.23
• 4.24
• 4.25
• 4.26
• 4.27
• 4.28
• 4.29
• 4.30
• 4.31
• 4.32
• 4.33.9M
• 4.34.8M
• 4.35.6M
• 4.36.2F

License

• commercial

CPE 2.3info

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CPE 2.2info

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