IRONSMITHINTEL
MEDIUMCVSS6.5
|
Actively Exploited
|CISA KEV|CVE-2022-20821|Auth: none — unauthenticated|Reboot: required|Manual only

Cisco IOS XR Open Port Vulnerability (CVE-2022-20821)

Cisco IOS XR software health check opens TCP port 6379 by default on activation. An attacker can connect to the Redis instance on the open port and allow access to the Redis instance that is running within the NOSi container.

Published May 26, 2022 · Updated May 17, 2026
Why patchRisk explained in plain English
Worst-case scenarioIf unpatched

A remote attacker, without authentication, can achieve partial data exposure, partial data tampering. Federal agencies are required to remediate by 2022-06-13 under CISA BOD 22-01.

How the attack worksNo clicks needed

This is a Information Disclosure (CWE-200) vulnerability in Cisco IOS XR. 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. Exploitation requires remote network access, low attack complexity, no authentication required, and no user interaction required.

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Phishing link

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Malicious file

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Server compromised

Am I affected?Quick check

Probably yes if any of these apply:

Network Security Team
Firewall Administrators
IT Security
Running ios xr: -
Real-world incidentsWhat we've seen

CISA added this CVE to the Known Exploited Vulnerabilities catalog on 2022-05-23 based on evidence of active exploitation in the wild. Federal agencies required to remediate by 2022-06-13.

How to patch

Manual remediation steps

1
Identify affected hosts: query inventory for network-security installs in scope.
2
Apply the vendor security update referenced in CVE-2022-20821's advisory. No specific KB/version is encoded yet — consult the linked MSRC/vendor URL.
3
Verify the fix per the vendor's published verification steps.
4
Document the remediation in your change ticket and re-scan with your vulnerability scanner to confirm closure.
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