CVE-2021-21973
Confirmed PUBLISHEDThe vSphere Client (HTML5) contains an SSRF (Server Side Request Forgery) vulnerability due to improper validation of URLs in a vCenter Server...
Recommended Action
Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
At a Glance
The vSphere Client (HTML5) contains an SSRF (Server Side Request Forgery) vulnerability due to improper validation of URLs in a vCenter Server plugin. A malicious actor with network access to port 443 may exploit this issue by sending a POST request to vCenter Server plugin leading to information disclosure. This affects: VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2).
- CVE Published
- Feb 24, 2021
- Exploitation Reported
- Mar 07, 2022
- CVSS
- 5.3 Medium
- EPSS
- —
Affected Versions
| Vendor | Product | Version | Status |
|---|---|---|---|
| n/a |
VMware vCenter Server
|
7.x before 7.0 U1c |
Affected |
| n/a |
VMware vCenter Server
|
6.7 before 6.7 U3l |
Affected |
| n/a |
VMware vCenter Server
|
6.5 before 6.5 U3n |
Affected |
| n/a |
VMware Cloud Foundation
|
4.x before 4.2 |
Affected |
| n/a |
VMware Cloud Foundation
|
3.x before 3.10.1.2 |
Affected |
CVE References
- vmware.com/security/advisories/VMSA-2021-0002.html vmware.com · CVE Record https://www.vmware.com/security/advisories/VMSA-2021-0002.html
Recommended Actions
- Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
- Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
- Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.
Known Exploited Vulnerability Sources
Catalogues that list this CVE as a known exploited vulnerability.
Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.
Learn about Pro API access| Source | Added |
|---|---|
| CISA First | 2022-03-07 00:00 UTC |
Scanner Artifacts
Nuclei and Metasploit references linked to this CVE.
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21973.yaml | Apr 25, 2025 |
Virtual Patch
Compensating WAF rules to help reduce exposure to this CVE. Rule content and deployable vendor exports are available with KEVIntel Enterprise.
KEVIntel does not currently have a virtual patch for this CVE. When available, KEVIntel virtual patches ship as deployable ModSecurity, Cloudflare, and AWS WAF rules.
Enterprise feature. Virtual patch rule content and deployable vendor exports (ModSecurity, Cloudflare, AWS WAF) are available to KEVIntel Enterprise users.
CVSS Scores
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
AV:N/AC:L/Au:N/C:P/I:N/A:N
Exploitation Status
Exploited in the wild
Recorded 2022-03-07 00:00:00 UTC · CISA
Proof of concept available
Recorded 2026-06-12 14:20:19 UTC · Nuclei Templates
Weaknesses (CWE)
-
Server-Side Request Forgery (SSRF)
Scanner Integrations
| Scanner | Reference | Detected |
|---|---|---|
| Nuclei | https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21973.yaml | Apr 25, 2025 |
Potential Proof of Concepts
These PoCs are unverified and could contain malware. Use at your own risk.
nuclei · Created Unknown
Timeline
Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.
-
14:20 UTC about 1 month ago14:20 UTC · about 1 month ago
Public PoC available
Public proof-of-concept code published
-
00:00 UTC about 1 year ago00:00 UTC · about 1 year ago
Nuclei template available
Scanner coverage available
-
00:00 UTC over 4 years ago00:00 UTC · over 4 years ago
Added to CISA KEV
Listed in the CISA Known Exploited Vulnerabilities catalog
-
16:42 UTC over 5 years ago16:42 UTC · over 5 years ago
CVE published
Vulnerability disclosed publicly
-
00:00 UTC over 5 years ago00:00 UTC · over 5 years ago
CVE ID reserved
Identifier reserved by the CNA
Automate This Intelligence with the Pro API
Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.
Pro API Example
GET /api/v2/pro/kevs/CVE-2021-21973
{
"cve_id": "CVE-2021-21973",
"title": "The vSphere Client (HTML5) contains an SSRF (Server Side Request Forgery) vul...",
"affected_vendor": "VMware",
"affected_product": "VMware vCenter Server, VMware Cloud Foundation",
"affected_versions": [
{ "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
],
"confidence": "Confirmed",
"cvss_score": 5.3,
"epss_score": null,
"exploit_status": {
"exploited_in_the_wild": true,
"active_exploitation_observed": false
},
"sensor_telemetry": { "...": "Pro API fields" },
"proof_of_concepts": [ "..." ],
"scanner_integrations": [ "..." ]
}