How to Fix CVE-2021-1497: Cisco HyperFlex HX Web Management Interface RCE

*By Sai Kiran Pandrala*

⚠️ Patch immediately. HyperFlex is hyperconverged infrastructure, controller compromise typically means access to every VM the cluster hosts.

What is CVE-2021-1497?

The web management interface of Cisco HyperFlex HX has a command injection vulnerability. An unauthenticated remote attacker can send crafted HTTP requests to specific management endpoints and execute commands as root on the HyperFlex controller. HyperFlex controllers manage the storage and compute fabric, RCE here means VM disk access, configuration tampering, and credential theft for the entire cluster.

Am I affected?

You are affected if you run Cisco HyperFlex HX at a version below the patched build in the Cisco PSIRT advisory. Check the HyperFlex Connect UI for the running version.

How to fix CVE-2021-1497

1. Open the Cisco PSIRT advisory linked below and identify the patched HX Data Platform build for your environment.
2. Download the patched release from the Cisco Software Download Center.
3. Apply the upgrade via the HX Data Platform Upgrade workflow in HyperFlex Connect.
4. Verify post-upgrade by checking the version in the UI.

Upgrade the affected Cisco platform

! Verify the running release on the device
show version
show inventory

! Stage the patched image from the Cisco Security Advisory: https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hyperflex-rce-TjjNrkpR
copy tftp://<fileserver>/<patched-image>.bin flash:

! Set the boot image and reload in a maintenance window
configure terminal
boot system flash:<patched-image>.bin
end
write memory
reload

! After reload, confirm the new image is running
show version | include image

Verify the fix landed

# 1. Confirm the running version matches the fixed-in version from the advisory:
#    https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hyperflex-rce-TjjNrkpR
#    Use the platform-specific version probe above.

# 2. Re-scan with your vulnerability scanner (Nessus, Qualys, Tenable, OpenVAS).
#    The scanner should no longer flag CVE-2021-1497 on the patched target.

# 3. Inspect recent service / kernel logs for crash loops or rollback events.
journalctl -u <service> --since "10 minutes ago"
dmesg --since "10 minutes ago"

If you can't patch immediately

Restrict HyperFlex management network access at the perimeter to a small administrative subnet. The HX management plane should never be on data-network VLANs or the internet.

How to verify the fix worked

HyperFlex Connect UI shows the patched HX Data Platform version. Run an internal vulnerability scan against the HX controller IPs.

Frequently asked questions

Is CVE-2021-1497 actively exploited?

Yes. CVE-2021-1497 is on the CISA Known Exploited Vulnerabilities catalog, so federal civilian agencies are required to patch on the published deadline. Most enterprises treat the same date as the practical floor.

What is the CVSS severity of CVE-2021-1497?

Critical. See the advisory for the full CVSS vector.

Where can I read the official advisory?

See https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hx-cmd-inject

Does the patch require a reboot?

It depends on the deployment. Service-only updates usually need a service restart; OS-level fixes require a full reboot. Check the vendor release notes for the exact post-upgrade steps.

References

• Official Cisco PSIRT advisory: https://sec.cloudapps.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-hx-cmd-inject
• NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-1497
• CISA KEV catalog entry: https://www.cisa.gov/known-exploited-vulnerabilities-catalog
• Related: How to Fix CVE-2021-1498

*This guide was assembled from the Cisco PSIRT advisory, NVD record, and CISA KEV listing on 2026-05-25. Always confirm against Cisco's advisory before applying changes in production.*