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Arista EOS DHCP Relay Forwards Crafted Reply Packets From Non-Helper-Address Sources to Clients Without Validation, Letting Unauthenticated Network Attackers Inject Arbitrary DHCP Responses to Hosts

Last refreshed2026-09-28

Status: NEW  |  Advisory ID: CVE-2026-73437

Key Details

CVECVE-2026-73437
CVSS Score / Version9.6 (Critical) / CVSS v3.1
Updated2026-09-17
CVSS VectorCVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
CVSS Proseattack vector is adjacent; attack complexity is low; privileges required is none; user interaction is none; scope is changed; confidentiality impact is high; integrity impact is high; availability impact is high.
Classified asCWE-345 (Insufficient Verification of Data Authenticity)

What to Know

On affected platforms running Arista EOS with Dynamic Host Configuration Protocol (DHCP) relay configured, an unauthenticated attacker with network access could send a crafted DHCP reply packet from an IP address that is not configured as a helper address, and the relay agent would forward it to clients without validating the source. This could allow the attacker to supply clients with malicious network configuration parameters, potentially resulting in traffic interception or denial of service for affected clients. (NVD)

References

SourceReference
NVDhttps://nvd.nist.gov/vuln/detail/CVE-2026-73437
CVEhttps://www.cve.org/CVERecord?id=CVE-2026-73437