CVE-2026-19655 Denial of service in EOS
An unauthenticated attacker can cause a denial of service by sending crafted packets to DHCP relay services configured with Option 82.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2026-19655?
CVE-2026-19655 is a high-severity denial of service vulnerability in Arista Networks EOS, published on 15 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
On affected platforms running Arista EOS with Dynamic Host Configuration Protocol (DHCP) relay/snooping configured with the information option (Option 82), or with the DHCP server configured with match criteria based on the information option, an unauthenticated attacker connected to a client-facing VLAN(s) where the relay is configured can send a specially crafted packet that causes the DHCP Relay service to restart.
Weakness: CWE-20
Which versions are affected by CVE-2026-19655?
How do I fix CVE-2026-19655?
No fix has been published for CVE-2026-19655 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2026-19655 being exploited?
There is no known exploitation of CVE-2026-19655 in the wild and no public exploit code.
Sources
Also known as GHSA-986v-7qw9-p5p6.