CVE intelligence and bounded remediation
CVE-2021-21985 — VMware vCenter Server Improper Input Validation Vulnerability
The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server. A malicious actor with network access to port 443 may exploit this issue to execute commands with unrestricted privileges on the underlying operating system that hosts vCenter Server.
- Severity
- Critical
- CVSS
- 9.8 (3.1)
- Published
- 2021-05-26
- CISA KEV
- Known exploited
- Ecosystem
- software/application
- Weaknesses
- CWE-918, CWE-20, CWE-470
Affected products
- vmware / vcenter_server / 6.5
Showing 1 representative product identities from 53 source matches. Confirm exact affected versions with the linked vendor and NVD evidence.
Matched remediation archetype
Server-side request forgery and unintended proxying
This catalog composition supplies bounded fallback guidance. Explicitly reviewed curated workflows load with the complete record below.
Check exposure
- Inventory server-side URL fetchers, webhooks, importers, previews, redirects, proxies, and protocol handlers reachable from untrusted input.
- Map egress paths to internal services, metadata endpoints, loopback, private address space, and privileged control planes.
- Review DNS resolution, redirect, proxy, credential-forwarding, and URL parsing behavior without requesting sensitive targets.
Remediate safely
- Replace arbitrary destinations with named integrations or a strict allowlist of schemes, hosts, ports, and paths.
- Resolve and validate every destination and redirect hop, then enforce egress policy independently of application checks.
- Remove ambient credentials and sensitive headers from fetchers; apply response size, time, and content limits.
Authoritative sources
Complete CVE record and remediation plan
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