# CVE-2026-73443: Other in EOS

> An attacker on the same network segment can replay VRRP advertisements to prevent failover, causing a denial of service for hosts using the virtual gateway.

- **Severity:** Medium 5.3 (`CVSS:4.0/AV:A/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/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:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-vq3p-3r98-j8w8

## What is CVE-2026-73443?

CVE-2026-73443 is a medium-severity vulnerability in Arista Networks EOS, published on 16 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 VRRPv2 IP-AH authentication configured, an unauthenticated attacker within the same layer 2 network segment on which VRRP is running can capture a legitimate authenticated VRRP advertisement and replay it indefinitely. Replayed advertisements can be used to advertise stale VRRP state, for example to prevent a backup router from taking over the virtual gateway after the original master has gone down, resulting in a denial of service for hosts using the virtual gateway address.

Weakness: CWE-294 (Authentication Bypass by Capture-replay)

## Which versions are affected by CVE-2026-73443?


## How do I fix CVE-2026-73443?

No fix has been published for CVE-2026-73443 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-73443 being exploited?

There is no known exploitation of CVE-2026-73443 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73443 and fix it if it is affected.

What it is: CVE-2026-73443 is a medium-severity vulnerability in Arista Networks EOS, published on 16 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-2026-73443 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-2026-73443/ (Markdown: https://insights.sbomify.com/CVE-2026-73443/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73443
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73443
- OSV: https://osv.dev/vulnerability/CVE-2026-73443

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73443/
Summaries are generated and may contain mistakes; the official description above is the record.