VMware vCenter Server CVE-2021-21972 (vSphere Client vRealize Operations plugin remote code execution, CISA KEV): which builds are fixed and what if I can't patch right away?

Applies to: vCenter Server 7.0 before U1c, 6.7 before U3l, 6.5 before U3n; VMware Cloud Foundation 4.x before 4.2, 3.x before 3.10.1.2

How it was checked: Compiled on 2026-10-30 from VMware/Broadcom advisory VMSA-2021-0002, NVD and the CISA KEV catalog; not reproduced by Exuvia.

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Fix

What it is: CVE-2021-21972 is a critical (CVSS 9.8) flaw in a vCenter Server plugin (for vRealize Operations) of the vSphere Client (HTML5). An attacker with network access to port 443 could run commands with unrestricted privileges on the underlying OS hosting vCenter. VMware published VMSA-2021-0002 on February 23, 2021; exploitation was reported soon after and the flaw is in CISA's KEV catalog (added November 3, 2021, ransomware use noted). The plugin is present in default installs, even without vROps. Am I affected: - vCenter Server 7.0 before 7.0 U1c, 6.7 before 6.7 U3l and 6.5 before 6.5 U3n. - VMware Cloud Foundation 4.x before 4.2 and 3.x before 3.10.1.2. - Check Help > About in the vSphere Client or the appliance management interface for the build. Fix: 1. Upgrade vCenter to 7.0 U1c, 6.7 U3l or 6.5 U3n or later; for Cloud Foundation use 4.2 or 3.10.1.2 or later. Today you should be on a currently supported vSphere release, as the 6.x lines are out of support. 2. If you can't patch immediately, VMware's advisory points to KB82374 for a workaround that disables the vulnerable plugin; follow that article, and treat it as temporary. 3. Never expose vCenter to the internet; restrict port 443 to management networks or a jump host/VPN. 4. If vCenter was reachable while unpatched, review the appliance for unexpected files and processes, new SSO or local accounts, and unfamiliar logins, and check connected ESXi hosts and VMs. Rebuild vCenter from a clean install if suspicious, and rotate vCenter SSO, service and integration credentials. Verify: Help > About shows a fixed or newer build, and port 443 on vCenter is unreachable from untrusted networks. Sources: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23599 https://nvd.nist.gov/vuln/detail/CVE-2021-21972 https://www.cisa.gov/known-exploited-vulnerabilities-catalog

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