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MediumCISA KEVExploited in the wildPublic exploit

Arista EOS tunnel decapsulation protocol verification flaw

IdentifiersCVE-2026-7473CWE-1023· Incomplete Comparison with Missing…

CVE-2026-7473 affects Arista Extensible Operating System (EOS) on affected platforms when tunnel decapsulation is configured, including VXLAN VTEPs, decap-groups, or GRE tunnel interfaces. The flaw causes the switch to incorrectly decapsulate and forward unexpected tunneled packets whose destination IP matches the device's configured decapsulation IP. The root cause is that EOS does not verify the tunnel protocol type before decapsulation, so a device configured to decapsulate one tunnel type can also accept and process other non-configured tunnel protocols sent to the same decapsulation IP. Arista has reported that the issue has been exploited in the wild.

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ANALYST BRIEF

Impact, mitigation & remediation

What it means. What to do now. Patch path, mitigations, and the assume-compromise checklist.

Impact

What an attacker gets, and what they’ve been doing with it.

Successful exploitation allows an attacker to inject unexpected tunneled traffic that the switch will decapsulate and forward into internal network segments, despite that tunnel protocol not being configured for that endpoint. This can result in unintended packet processing, bypass of expected tunnel-type restrictions, and unauthorized reachability into networks behind the decapsulation device. The primary impact is improper forwarding of attacker-supplied traffic across trust boundaries rather than direct code execution on the switch.

Mitigation

If you can’t patch tonight, do this now.

Mitigate by filtering traffic to the decapsulation IP so that only legitimate tunnel traffic is permitted. Arista recommends applying ACLs either on upstream devices before the traffic reaches the tunnel endpoint or directly on the decapsulation switch. Filters should selectively allow only expected tunnel protocols and, where applicable, expected UDP ports, or block non-authorized tunnel traffic destined for the decapsulation IP. On some hardware families, implementing mitigation on the decapsulation switch requires TCAM profile changes and platform-specific ACL mechanisms such as MAC ACLs with User Defined Fields or IPv6 PACLs.

Remediation

Patch, then assume compromise.

Arista states that no software upgrade path or hotfix is planned for CVE-2026-7473 because a protocol-verification fix could break existing deployments. Customers should follow Arista's published mitigation guidance and contact Arista TAC if assistance is required. Where organizational policy requires KEV remediation, apply vendor-recommended mitigations immediately and validate that only intended tunnel traffic can reach decapsulation IPs.
PUBLIC EXPLOITS

Exploits

No public exploits tracked yet. Mallory keeps watching.

VALID 0 / 0 TOTALView more in app

No public exploit code observed for this vulnerability.

EXPOSURE SURFACE

Affected products & vendors

Products and vendors Mallory has correlated with this vulnerability. Open in Mallory to drill down to specific CPE configurations and version ranges.

VendorProductType
Arista NetworksEosoperating_system

Vendor-confirmed product mapping. Mallory continuously reconciles this list against your asset inventory.

ACTIVITY FEED

Recent activity

12 sources tracked across advisories, community write-ups, and news. New activity surfaces here as Mallory finds it.

12 SOURCESView more in app
What this page doesn’t show

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Exposure mapping

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Threat actor evidence

Every observed campaign linking this CVE to a named adversary.

Associated malware

Malware families riding this exploit, with evidence and IOCs.

Detection signatures1

YARA, Sigma, Snort, and vendor rules, auto-deployed to your SIEM.

Vendor-by-vendor mapping

Cross-references every affected SKU, including bundled OEM variants.

Social activity8

Community discussion across Reddit, Mastodon, and other social sources.

EXTERNAL REFERENCES
MITRE CVE
cve.org · CVE-2026-7473
NVD
nvd.nist.gov/vuln/detail/CVE-2026-7473
MITRE CWE · CWE-1023
Incomplete Comparison with Missing Factors
Vendor Advisory
arista.com/en/support/advisories-notices/security-advisory/24005-security-advisory-0137
US Government Resource
cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2026-7473