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ExploitedIn CISA KEVFix available

CVE-2021-21973

Exploitation confirmed. First attested on 2022-03-07 by CISA-ADP, CISA KEV, GCVE · kevintel.

  • Published2021-02-24
  • WeaknessCWE-918

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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).

Timeline

dates in UTC
  1. 2021-02-2417:15CVE publishedNVD
  2. 2022-03-07Added to the CISA KEV catalogCISA KEV
  3. 2022-03-07Listed as exploited by GCVEGCVE
  4. 2022-03-07Exploitation first reportedCISA KEV
  5. 2024-02-1616:16SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-04 09:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-21973?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-21973?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Vmware vcenter server
BranchAffectedFixed in
6.5= 6.5no fix published
6.7= 6.7no fix published
7.0= 7.0no fix published
Vmware cloud foundation
BranchAffectedFixed in
4.x≥ 4.0, < 4.24.2
3.x≥ 3.0, < 3.10.1.23.10.1.2

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA2 products

As vmware, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • VMware vCenter Server
    Affected
    • = 7.x before 7.0 U1cno fix stated
    • = 6.7 before 6.7 U3lno fix stated
    • = 6.5 before 6.5 U3nno fix stated
  • VMware Cloud Foundation
    Affected
    • = 4.x before 4.2no fix stated
    • = 3.x before 3.10.1.2no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2021-02-24

Fix

  1. CISA’s required action: Apply updates per vendor instructions.due 2022-03-21

Advisories and patches

Detection

read 2026-11-03 22:42 UTC
Nuclei template
available
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
1 repository, unverifiedfreakanonymous/CVE-2021-21973-Automateme
PoC-in-GitHub
Metasploit modules
none listed
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2022-03-07
Patch Due Date
2022-03-21
Ransomware Use
Unknown
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Published
2021-02-24
Last Modified
2026-06-17
NVD status
Analyzed
GitHub Advisory
GHSA-5j6h-79mj-qfq2

Frequently asked questions

What is CVE-2021-21973?

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).

Is CVE-2021-21973 actively exploited?

Yes. CVE-2021-21973 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2022-03-21.

What is the CVSS score for CVE-2021-21973?

CVE-2021-21973 has a CVSS v3 base score of 5.3 (MEDIUM severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

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