---
id: "CVE-2026-121291"
page: "https://infrastack.ai/live/CVE-2026-121291"
kind: "vulnerability"
aliases: ["CVE-2026-121291"]
title: "Arista EOS: crafted RPKI Error Report stalls ROA publication and BGP origin validation"
severity: "high"
cvss: 8.3
epss: null
exploited: false
status: "open"
category: "infrastructure"
products: [{"name": "EOS", "fixed": ["4.35.7M", "4.36.3M"], "affected": ">= 4.35.0F, <= 4.35.6M; >= 4.36.0F, <= 4.36.2F; 4.37.0F", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["arista", "bgp", "eos", "infrastructure", "network-devices", "routing", "rpki"]
not_affected_if: ["no-rpki-configured"]
published_at: "2026-11-10T20:18:54+00:00"
first_seen_at: "2026-11-10T20:46:03+00:00"
updated_at: "2026-11-10T20:56:28+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-121291", "first_seen_at": "2026-11-10T20:46:03+00:00"}, {"source": "analyst", "url": "https://www.arista.com/en/support/advisories-notices/security-advisory/25044-security-advisory-0222", "first_seen_at": "2026-11-10T20:56:28+00:00", "cites": ["https://www.arista.com/en/support/advisories-notices/security-advisory/25044-security-advisory-0222"]}]
exploit_sources: []
---

# Arista EOS: crafted RPKI Error Report stalls ROA publication and BGP origin validation

Link for people: https://infrastack.ai/live/CVE-2026-121291 (this .md is for agents)

A crafted Error Report can leave EOS stuck believing a cache reset is in progress. While stuck, ROA publication, withdrawal reconciliation and BGP origin-validation updates are blocked.

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

## Affected

- vendor:EOS affected >= 4.35.0F, <= 4.35.6M; >= 4.36.0F, <= 4.36.2F; 4.37.0F fixed 4.35.7M, 4.36.3M

## How to check

On the switch run 'show bgp rpki cache': exposed only if EOS is 4.37.0F, 4.36.0F-4.36.2F or 4.35.0F-4.35.6M AND an RPKI cache is configured under router bgp with an RPKI-RTR session established. Signs it happened: 'grep "RPKI-4-CACHE_ERROR: Received" /var/log/eos' (Internal Error / No Data Available), 'show bgp rpki cache cache1 counters errors', and a 'Last full sync' time in 'show bgp rpki cache cache1' that no longer advances.

## Fix

Upgrade to EOS 4.36.3M or later (4.36 train) or 4.35.7M or later (4.35 train). No fixed release is named for 4.37.0F in the advisory; check Arista.

## Timeline

- 2026-11-10T20:46:03+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-121291
- 2026-11-10T20:56:28+00:00 analyst https://www.arista.com/en/support/advisories-notices/security-advisory/25044-security-advisory-0222 — Arista SA 0222 (read via fetch tool, summarised); NVD lists same versions. Search/X not used. 4.37.0F affected, no fixed 4.37 release stated.

## Documents

- [advisory] Arista Security Advisory 0222 https://www.arista.com/en/support/advisories-notices/security-advisory/25044-security-advisory-0222

## From the sources

A crafted Error Report can leave EOS stuck believing that a cache reset is in progress, preventing ROA publication, withdrawal reconciliation, and BGP origin-validation updates.

---

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