Unauthenticated network access via fallback VLAN multi-host logic
Published Jun 4, 2026 · Updated Jun 4, 2026
Authentication bypass in Arista Networks EOS allows physically proximate attackers to gain network access through an 802.1X-controlled switch port. The 802.1X multi-host logic admits traffic from other unauthenticated MAC addresses when an EAPOL-capable device is present in a configured fallback VLAN. Exploitation requires authenticator auto mode with multi-host enabled and a fallback VLAN; the documented consequence is unauthorized network access.
Summary
What happened
Authentication bypass in Arista Networks EOS allows physically proximate attackers to gain network access through an 802.1X-controlled switch port. The 802.1X multi-host logic admits traffic from other unauthenticated MAC addresses when an EAPOL-capable device is present in a configured fallback VLAN. Exploitation requires authenticator auto mode with multi-host enabled and a fallback VLAN; the documented consequence is unauthorized network access.
The record
- CVE
- CVE-2024-6858
- Published
- Jun 4, 2026
- Updated
- Jun 4, 2026
- Vendor
- Arista Networks
- Product
- Arista Extensible Operating System (EOS)
- Classifications
- CWE-287, CWE-1287, CAPEC-115
- Attack vector
- adjacent
- Privileges
- unauthenticated
Timeline
How it unfolded
- Jun 4, 2026CVE publishedPublication date reported by the CVE source.
- Jun 4, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
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- Affected versionversion=4.28.10 <=4.28.10.1M
- Affected versionversion=4.29.0 <=4.29.7M
- Affected versionversion=4.30.0 <=4.30.5M
- Affected versionversion=4.31.0 <=4.31.1F
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
What attackers are doing with it
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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