# CVE-2026-73437: Missing authorization in EOS

> An unauthenticated attacker can send crafted DHCP replies to intercept traffic or cause denial of service on clients when DHCP relay is configured.

- **Severity:** Medium 6.5 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:L/VA:N/SC:H/SI:H/SA:H`)
- **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:** 17 Sep 2026
- **Also known as:** GHSA-qg3p-gw27-mvmj

## What is CVE-2026-73437?

CVE-2026-73437 is a medium-severity missing authorization 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 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.

Weakness: CWE-345 (Insufficient Verification of Data Authenticity)

## Which versions are affected by CVE-2026-73437?


## How do I fix CVE-2026-73437?

No fix has been published for CVE-2026-73437 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-73437 being exploited?

There is no known exploitation of CVE-2026-73437 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73437 and fix it if it is affected.

What it is: CVE-2026-73437 is a medium-severity missing authorization 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-2026-73437 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-2026-73437/ (Markdown: https://insights.sbomify.com/CVE-2026-73437/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73437
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73437
- OSV: https://osv.dev/vulnerability/CVE-2026-73437

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73437/
Summaries are generated and may contain mistakes; the official description above is the record.