On affected platforms running Arista EOS where a tunnel decapsulation configuration—such as VXLAN (Virtual Extensible LAN), decap-groups, or a GRE (Generic Routing Encapsulation) tunnel interface—is present, the switch will incorrectly decapsulate and forward other unexpected tunneled packet with a destination IP matching its configured decapsulation IP. This occurs because the switch does not verify the tunnel protocol type, potentially leading to the unexpected processing of non-configured tunnel traffic.
This issue has been reported as being exploited in the wild.
| Product | Vendor Advisory | Solution File | Added | Published |
|---|---|---|---|---|
| Arista Eos | — | Apply ACLs on upstream devices or on the decapsulation switches to selectively allow only legitimate tunnel traffic or to selectively block malicious tunnel traffic. | Jun 25, 2026 | May 5, 2026 |
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