---
id: "CVE-2026-121370"
page: "https://infrastack.ai/live/CVE-2026-121370"
kind: "vulnerability"
aliases: ["CVE-2026-121370"]
title: "Arista EOS: unauthenticated PTP traffic can cause denial of service"
severity: "critical"
cvss: 9.2
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: []
ecosystems: []
tags: ["arista-eos", "infrastructure", "network-switches", "ptp"]
not_affected_if: ["ptp-not-configured"]
published_at: "2026-11-10T20:18:56+00:00"
first_seen_at: "2026-11-10T20:46:04+00:00"
updated_at: "2026-11-10T20:50:02+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121370", "first_seen_at": "2026-11-10T20:46:04+00:00"}, {"source": "analyst", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121370", "first_seen_at": "2026-11-10T20:50:02+00:00", "cites": ["https://nvd.nist.gov/vuln/detail/CVE-2026-121370"]}]
exploit_sources: []
---

# Arista EOS: unauthenticated PTP traffic can cause denial of service

Link for people: https://infrastack.ai/live/CVE-2026-121370 (this .md is for agents)

Arista EOS switches running Precision Time Protocol (PTP) can be knocked over by an unauthenticated attacker who sends traffic to a PTP-enabled port. The result is a denial of service, not code execution or data access.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether PTP is configured on the switch (the sources do not name the exact command; unknown)
- Check the EOS version in use with `show version` (affected ranges unknown from the sources)

## Timeline

- 2026-11-10T20:46:04+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121370
- 2026-11-10T20:50:02+00:00 analyst https://nvd.nist.gov/vuln/detail/CVE-2026-121370 — Arista's own advisory for CVE-2026-121370 (published about 30 min ago, part of the Nov 10 batch) is not indexed yet. The arista.com index page sits behind a client challenge and search returned nothing for this id. Only NVD is linked, and it has no version ranges. Nothing verified. Revisit when the advisory appears: it should give affected EOS trains, fixed releases, PTP check/mitigation. CVSS v4 9.2 from psirt@arista.com is the vendor's own score. Availability only (VA:H/SA:H). Severity unchanged. X not searched, and no discussion found.

## Documents

- [describes] NVD CVE-2026-121370 https://nvd.nist.gov/vuln/detail/CVE-2026-121370

## From the sources

On affected platforms running Arista EOS with Precision Time Protocol (PTP) configured, an unauthenticated attacker with network access to a PTP-enabled port can create a denial of service (DoS) condition by sending traffic to the system.

---

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