CVE-2022-20821: Cisco IOS XR Open Port Vulnerability
- Is it exploited?
Yes. CISA added it to the Known Exploited Vulnerabilities catalog on 23 May 2022, 3 days before the CVE record was published.
- How likely is exploitation in the next 30 days?
- 11.5%
EPSS score, percentile 96 of all scored records
- How severe?
- 6.5 Medium
CVSS v3.1 base score, given by the CNA
- What should I do?
Required action (CISA), due 13 Jun 2022: Apply updates per vendor instructions.
- Which versions are affected?
Affected: unspecified
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
What to do
Required action, set by CISA
Apply updates per vendor instructions.
CISA due date for this action: 13 June 2022.
Advisories and patches
Linked from CISA's catalog entry
Affected products and versions
As listed in the CVE record.
| Status | Versions |
|---|---|
| Affected | unspecified |
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
About this vulnerability
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.
Summary: CISA's KEV catalog, as of 28 Oct 2026.
- CISA added CVE-2022-20821 to its Known Exploited Vulnerabilities (KEV) catalog on 23 May 2022.
- CISA's ransomware flag for this entry is "Unknown": no evidence of ransomware use in the catalog, which is not proof of none.
- The due date CISA sets for the required action is 13 Jun 2022.
- The CVE record was published on 26 May 2022, 3 days after it was added to KEV.
- The CVE record carries a CVSS v3.1 base score of 6.5 (Medium), given by its CNA.
- FIRST's EPSS model puts the probability of exploitation in the next 30 days at 11.5% (percentile 96), as of 28 Oct 2026.
- CISA's SSVC assessment in the CVE record: exploitation active, automatable yes, technical impact partial.
Source: CISA Known Exploited Vulnerabilities (KEV) catalog, 2026.10.28, as of 28 Oct 2026; CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026; FIRST Exploit Prediction Scoring System (EPSS), v2026.06.15, as of 28 Oct 2026. About the data.
Description
Cisco IOS XR Software Health Check Open Port Vulnerability
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.
Source: CVE List V5 (CVE Program), cve_2026-10-28_0000Z, as of 28 Oct 2026. About the data.
Weakness
CWE and CAPEC are maintained by MITRE; the entries are those named in the CVE record and the KEV entry.
Timeline
| Date | Event |
|---|---|
| 23 May 2022 | Added to CISA KEV |
| 26 May 2022 | CVE record published |
| 13 Jun 2022 | CISA due date for the required action |
| 21 Oct 2025 | CVE record last updated |
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