What this checks: whether a VMware vCenter host runs a version affected by unauth SSRF in a vCenter Server plugin. Read-only: it fingerprints VMware vCenter and reads the version, no exploitation.
3. Detection — reads the VMware vCenter version from the version exposed at /sdk, compares to 7.0 U1c (build 17327517). Flags vulnerable on an affected build. No exploitation.
1. Target List — paste your VMware vCenter URLs here, one per line (e.g. https://host.example.com).
Overview
This workflow finds VMware vCenter Server and sorts each host by whether its version and build fall below the CVE-2021-21973 floor in the graph. CVE-2021-21973 is server-side request forgery in a vCenter plugin caused by improper URL validation. This check never sends a crafted plugin request. Give it hostnames, IP addresses, or URLs you are authorised to test. The workflow GETs /sdk, fingerprints vCenter from markers in that response, parses the VMware vCenter Server version and build- number, and compares the tuple to 7.0 U1c build 17327517. Every host comes back affected or not, so a fleet advisory becomes an evidenced list for exposure management. There is no SOAP body, no plugin hit, and no SSRF confirm.
Run it on a schedule when management planes change. A rebuilt VCSA that landed on an older 7.0 build is the reason the same fingerprint stays useful.
Pipeline
Read the target list. Hosts, URLs, or ranges, one per line, become the scope.
GET /sdk on each host and fingerprint vCenter from response markers such as VMware vCenter Server, vim.ServiceInstance, and build-.
Parse the version and build string and compare the tuple to the CVE-2021-21973 floor in the graph (7.0 U1c build 17327517).
Collect the per-host rows: product match, version, vulnerable flag, and any fetch error.
Emit the summary counts: hosts checked, product hits, vulnerable, and errors.
Inputs
Target scope. Hostnames, IP addresses, CIDR ranges, or URLs, one per line. Full URLs and host:port entries work too, since the workflow normalizes each into a bare host. Point it at scope you are authorised to test.
Outputs
results.jsonl. One row per host: URL, whether vCenter was detected, the version read, the vulnerable flag, and detail text.
findings.jsonl. The same per-host verdict shaped for triage, with severity set from the vulnerable flag.
summary.json. Counts across the list: targets, product hits, vulnerable, and errors, plus the detection notes from the graph.
Integrations
HTTP. Unauthenticated GET of /sdk only. No SOAP RetrieveServiceContent body and no plugin SSRF probe.
Sample output
The records below are illustrative and do not come from a real run. They show one vCenter host below the graph floor, one at or above 7.0 U1c build 17327517, and one host that is not the product.
Hosts whose parsed version and build tuple fall below 7.0 U1c build 17327517, the single floor coded in the graph. The compare uses the string the /sdk response itself served.
Does an affected row mean the plugin SSRF worked?
No. The check only GETs /sdk and reads version and build. It does not post a SOAP body, does not hit a plugin URL, and does not confirm SSRF.
Is this check safe on production?
Yes. It is a read-only unauthenticated GET of /sdk. It does not log in or trigger a server-side fetch.
Does the check need credentials?
No. It fingerprints the public /sdk surface the way an external scanner would.
What is CVE-2021-21973?
Server-side request forgery in a VMware vCenter Server plugin from improper URL validation. This workflow maps hosts to that CVE by version and build exposure only.