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CVE-2026-7473 is an Arista Extensible Operating System (EOS) vulnerability affecting certain EOS-based R-series switches when they are configured as tunnel decapsulation endpoints, including VXLAN VTEPs, GRE tunnel interfaces, or decap-groups. The switch validates the outer destination IP against its configured decapsulation IP but does not verify the tunnel protocol type before decapsulating and forwarding traffic. As a result, a device configured to decapsulate one tunnel type can incorrectly accept, decapsulate, and forward packets encapsulated with a different, non-configured tunnel protocol, provided the packet is addressed to the configured decapsulation IP. Reported examples include acceptance of unexpected formats such as GRE, VXLAN, IP-in-IP, NVGRE, or GUE depending on configuration. The flaw is configuration-dependent rather than version-dependent and has been reported by Arista as exploited in the wild.
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1 valid exploit after Mallory filtered fakes, detection scripts, and README-only repos.
This repository is a small standalone Python proof-of-concept exploit for CVE-2026-7473 affecting Arista EOS tunnel decapsulation behavior. The repo contains three files: a MIT license, a README with vulnerability description/usage/mitigation guidance, and a single executable script, arista_tunnel_bypass.py, which is the main entry point. The Python script uses Scapy to craft raw network packets for multiple tunnel types. Based on the visible code and CLI flow, it supports generating GRE, VXLAN, and GUE packets directly, and the truncated portions strongly indicate additional support for IP-in-IP and NVGRE-related bypass tests. The exploit logic is centered on sending an unexpected tunnel protocol to a switch whose decapsulation IP matches the outer destination IP, attempting to trigger improper decapsulation and forwarding of the inner packet. This demonstrates the core vulnerability: missing tunnel protocol type verification on affected Arista EOS devices. Capabilities include: building randomized outer source IPs, targeting a user-supplied decapsulation IP, embedding simple inner payloads (UDP, Ethernet/IP, ICMP), and running several exploit modes such as vxlan-gre, gre-vxlan, gre-ipip, gue, nvgre, or all. The script also includes a check-config mode, but the README and code indicate scanning is not fully implemented and manual identification of vulnerable configuration is still required. Operationally, this is an active network exploit/validation tool rather than malware or a post-exploitation implant. It does not establish persistence or a shell; instead, it validates whether unexpected tunneled traffic is decapsulated and forwarded. Because it contains working packet-generation and exploit routines but only basic hardcoded payloads, the maturity is best classified as OPERATIONAL.
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25 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.
A configuration-dependent vulnerability in Arista EOS switches where tunnel decapsulation checks the destination address but not the tunnel protocol type, allowing improperly decapsulated traffic to be forwarded into internal network segments.
A vulnerability in Arista EOS tunnel decapsulation handling that can allow unexpected tunneled packets to be accepted and processed without proper tunnel protocol verification, potentially causing traffic misrouting or security bypass.
A tunnel decapsulation weakness in Arista EOS that causes switches to forward unexpected tunneled packets due to missing protocol type verification.
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Cross-references every affected SKU, including bundled OEM variants.
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