# CVE-2026-73450: Security Advisory 0161

> An unauthenticated attacker can cause traffic interruption by sending crafted packets to interfere with MLAG dual-primary detection on Arista EOS devices.

- **Severity:** High 7.0 (`CVSS:4.0/AV:A/AC:L/AT:P/PR:N/UI:N/VC:N/VI:L/VA:H/SC:N/SI:N/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:** 16 Sep 2026
- **Updated:** 17 Sep 2026
- **Also known as:** GHSA-w26w-6gr3-j89v

## What is CVE-2026-73450?

CVE-2026-73450 is a high-severity denial of service 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 MLAG Dual Primary Detection configured, an unauthenticated attacker with access to the Dual Primary Detection network segment can send specially crafted packets to interfere with the dual-primary state. If the MLAG primary switch fails while these packets are present, the secondary switch incorrectly concludes it is in a dual-primary condition and err-disables its interfaces, leading to a traffic interruption.

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

## Which versions are affected by CVE-2026-73450?


## How do I fix CVE-2026-73450?

No fix has been published for CVE-2026-73450 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-73450 being exploited?

There is no known exploitation of CVE-2026-73450 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-73450 and fix it if it is affected.

What it is: CVE-2026-73450 is a high-severity denial of service 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-2026-73450 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-2026-73450/ (Markdown: https://insights.sbomify.com/CVE-2026-73450/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-73450
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-73450
- OSV: https://osv.dev/vulnerability/CVE-2026-73450

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-73450/
Summaries are generated and may contain mistakes; the official description above is the record.