---
id: "CVE-2022-20821"
kind: "vulnerability"
aliases: ["CVE-2022-20821"]
title: "Cisco IOS XR: Cisco IOS XR Open Port Vulnerability"
severity: "high"
cvss: 6.5
epss: 0.11471
exploited: true
status: "open"
category: "infrastructure"
products: [{"name": "Cisco IOS XR", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["cisco", "exploited", "infrastructure", "ios-xr", "network-devices"]
not_affected_if: ["default-config"]
published_at: "2022-05-23T00:00:00+00:00"
first_seen_at: "2026-10-23T19:11:52+00:00"
updated_at: "2026-10-23T21:57:35+00:00"
sources: [{"source": "kev", "url": "https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2022-20821", "first_seen_at": "2026-10-23T19:11:52+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2022-20821", "first_seen_at": "2026-10-23T19:13:45+00:00"}, {"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2022-20821", "first_seen_at": "2026-10-23T21:57:35+00:00"}]
---

# Cisco IOS XR: Cisco IOS XR Open Port Vulnerability

Cisco IOS XR opens TCP port 6379 by default when the software health check is activated, exposing an internal Redis instance running in the NOSi container. An attacker who connects to that port can access the Redis instance.

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

## Affected

- vendor:Cisco IOS XR affected ? fixed ?

## Fix

Apply the updates from Cisco per the vendor instructions; the fixed versions are not stated in the sources.

## Timeline

- 2026-10-23T19:11:52+00:00 kev https://www.cisa.gov/known-exploited-vulnerabilities-catalog?search_api_fulltext=CVE-2022-20821
- 2026-10-23T19:13:45+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2022-20821
- 2026-10-23T21:57:35+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2022-20821

## From the sources

A vulnerability in the health check RPM of Cisco IOS XR Software could allow an unauthenticated, remote attacker to access the Redis instance that is running within the NOSi container. This vulnerability exists because the health check RPM opens TCP port 6379 by default upon activation. An attacker could exploit this vulnerability by connecting to the Redis instance on the open port. A successful exploit could allow the attacker to write to the Redis in-memory database, write arbitrary files to the container filesystem, and retrieve information about the Redis database. Given the configuration of the sandboxed container that the Redis instance runs in, a remote attacker would be unable to execute remote code or abuse the integrity of the Cisco IOS XR Software host system.

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_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_