Arista Extensible Operating System Incomplete Comparison with Missing Factors Vulnerability

[ Why it matters ]Priority signals

• Exploited in the wild: on CISA's Known Exploited Vulnerabilities list since 2026-06-09

[ Description ]Official 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.

CISA: Arista Extensible Operating System (EOS) contains an incomplete comparison with missing factors vulnerability when the switch incorrectly decapsulate and forwards other unexpected tunneled packet with a destination IP matching its configured decapsulation IP.

[ Fixes ]Fixes and patches

CISA required action (US federal deadline 23 Jun 2026): Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

No fix or interim patch is linked from our sources yet. Check the vendor references below and limit exposure of affected systems until a fix is available.

[ References ]References

• www.arista.com/en/support/advisories-notices/security-advisory/22872-security-advisory-…Broken Link
• www.arista.com/en/support/advisories-notices/security-advisory/24005-security-advisory-…MitigationVendor Advisory
• www.cisa.gov/known-exploited-vulnerabilities-catalogUS Government Resource