---
id: "CVE-2026-120979"
page: "https://infrastack.ai/live/CVE-2026-120979"
kind: "vulnerability"
aliases: ["CVE-2026-120979"]
title: "Arista Pathfinder: crafted BGP-LS packet disrupts WAN path selection"
severity: "high"
cvss: 8.1
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "eos", "fixed": ["4.37.0F", "4.36.3M", "4.35.7M", "4.34.9M", "4.33.11M"], "affected": "<= 4.36.2F, <= 4.35.6M, <= 4.34.8M, <= 4.33.10M, all 4.32.x", "ecosystem": "vendor"}]
ecosystems: []
tags: ["arista", "awe", "bgp-ls", "cloudeos", "eos", "infrastructure", "network", "pathfinder", "wan"]
not_affected_if: ["fixed-eos-version", "no-bgp-ls-dps", "no-bgp-ls-peer", "no-pathfinder", "not-pathfinder-role"]
published_at: "2026-11-10T20:18:53+00:00"
first_seen_at: "2026-11-10T20:46:03+00:00"
updated_at: "2026-11-10T21:00:19+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-120979", "first_seen_at": "2026-11-10T20:46:03+00:00"}, {"source": "analyst", "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/25034-security-advisory-0212", "first_seen_at": "2026-11-10T21:00:19+00:00", "cites": ["https://www.arista.com/en/support/advisories-notices/security-advisory/25034-security-advisory-0212"]}]
exploit_sources: []
---

# Arista Pathfinder: crafted BGP-LS packet disrupts WAN path selection

Link for people: https://infrastack.ai/live/CVE-2026-120979 (this .md is for agents)

An attacker with an authenticated BGP-LS session to an Arista EOS device configured for Dynamic Path Selection can send a crafted BGP packet. This causes incorrect WAN path selection and disrupts traffic forwarding.

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

## Affected

- vendor:eos affected <= 4.36.2F, <= 4.35.6M, <= 4.34.8M, <= 4.33.10M, all 4.32.x fixed 4.37.0F, 4.36.3M, 4.35.7M, 4.34.9M, 4.33.11M

## How to check

Exposed only if all are true: (1) EOS version is 4.36.2F or lower in 4.36.x, 4.35.6M or lower in 4.35.x, 4.34.8M or lower in 4.34.x, 4.33.10M or lower in 4.33.x, any 4.32.x, or an End-of-Support train; (2) 'show bgp link-state summary' shows at least one BGP-LS peer in Estab state; (3) 'show adaptive-virtual-topology path | section Role:' prints 'Role: pathfinder'. If BGP-LS is not configured, no peer is established, or the role is edge, zone transit, region transit or unknown, the device is not affected. Signs of abuse: unexpected active-path changes or a high rate of SFE-6-PATH_ACTIVE / SFE-6-PATH_INACTIVE syslog messages ('show logging | include SFE-6-PATH_ACTIVE|SFE-6-PATH_INACTIVE'). Arista states there are no configuration-level mitigations that fully resolve this without upgrading.

## Fix

Upgrade EOS to 4.37.0F or later, 4.36.3M, 4.35.7M, 4.34.9M or 4.33.11M (or later in the same train). No hotfix. 4.32.x and End-of-Support trains have no listed fix, so move to a fixed train.

## Timeline

- 2026-11-10T20:46:03+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-120979
- 2026-11-10T21:00:19+00:00 analyst https://www.arista.com/en/support/advisories-notices/security-advisory/25034-security-advisory-0212 — Read Arista Security Advisory 0212 (vendor, Nov 10 2026): affected/fixed EOS versions, exact check commands, no mitigation, no hotfix. Not exploited per Arista; no PoC. Social search skipped (new advisory, no CVE-id posts expected).

## Documents

- [advisory] Arista Security Advisory 0212 https://www.arista.com/en/support/advisories-notices/security-advisory/25034-security-advisory-0212

## From the sources

This vulnerability affects customers using Arista Pathfinder for WAN path selection with Border Gateway Protocol-Link State (BGP-LS) configured for Dynamic Path Selection (DPS). On affected platforms running Arista EOS with BGP-LS configured for DPS, an attacker who has established an authenticated BGP-LS session with the device can send a specially crafted BGP packet to cause incorrect WAN path selection and disrupt traffic forwarding.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_