# 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.

- **Severity:** High 7.1 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 15 Sep 2026
- **Updated:** 16 Sep 2026
- **Also known as:** GHSA-986v-7qw9-p5p6

## 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 (Improper Input Validation)

## 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.

## Is CVE-2026-19655 being exploited?

There is no known exploitation of CVE-2026-19655 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-19655 and fix it if it is affected.

What it is: 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.
Exploitation: There is no known exploitation of CVE-2026-19655 in the wild and no public exploit code.

Affected product: Arista Networks EOS. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-19655/ (Markdown: https://insights.sbomify.com/CVE-2026-19655/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-19655
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-19655
- OSV: https://osv.dev/vulnerability/CVE-2026-19655

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-19655/
Summaries are generated and may contain mistakes; the official description above is the record.