Critical severity · published Sep 15, 2026
CVE-2026-73437
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/destinat
9.6
CVSS
0.2%
EPSS
No
On KEV
Description
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.
CVSS vector
CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H
Attack vector
Adjacent
Complexity
Low
Privileges
None
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Changed
Exploitation
Is it being used?
Exploit prediction (EPSS)0.2% · higher than 11% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
EO
EOS · Arista Networks
4.36.0 through 4.36.1F; 4.35.0 through 4.35.5M; 4.34.0 through 4.34.7.1M; 4.33.0 through 4.33.9M · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-73437
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-73437
www.arista.com
https://www.arista.com/en/support/advisories-notices/security-advisory/24712-security-advisory-0156
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