CVE-2021-21972
The vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin. 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. 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).
- CVSS
- 9.8Criticalscored by CISA
- Exploited in the wild
- Yes, in CISA KEV since 3 Nov 2021CISA deadline for US federal agencies: 17 Nov 2021known use in ransomware campaignspublic exploit code
- EPSS
- 99.9%chance of exploitation in the next 30 daystop 0.1% of scored CVEsFIRST score of 11 Nov 2026
- Fix
- Patch availablesee the advisories in the references
- Published
- 24 Feb 2021analysed here 12 Nov 2026
Do first. Apply updates per vendor instructions. (CISA's required action for this KEV entry)
Summary
Triage
The summary, impact and action text on this page are written by our AI analysis pipeline, or taken from the NVD description when a CVE was imported from NVD. They are not the vendor's wording: check them against the sources. A longer AI executive summary and technical analysis are generated for signed-in accounts on the Max plan.
Affected products
| Product | Affected versions | Vendor says fixed in |
|---|---|---|
| VMware Cloud Foundation | 4.x before 4.23.x before 3.10.1.2Vendor says fixed in: not stated | |
| VMware vCenter Server | 7.x before 7.0 U1c6.7 before 6.7 U3l6.5 before 6.5 U3nVendor says fixed in: not stated |
As published in the CVE Program record. A version outside these ranges is not a statement that it is unaffected — vendors sometimes understate a range, and distribution-backported builds carry upstream numbers that do not reflect what was patched into them.
Products named in our analysis
- vmware:cloud_foundation
- vmware:vcenter_server
Fix and mitigation
WAF and other mitigations
Can a WAF block it? Yes. Path traversal sends `../` sequences in the request, which WAF rules catch, including the common encodings.
Also consider: canonical path validation
Based on the weakness type only; no CVE-specific evidence yet. We check Cloudflare, AWS, Google Cloud Armor and Azure; for Akamai, Imperva, Fastly, F5, ask your vendor.
Remediation steps (AI-written)
Step-by-step remediation is generated for accounts on the Max plan, for CVEs that match a technology in their stack. Add this technology to your stack to see the fix checklist.
Exploitation evidence
- CISA KEV catalog
- Listed since 3 Nov 2021. Known use in ransomware campaigns.
- CISA due date
- 17 Nov 2021, the remediation deadline for US federal agencies
- CISA required action
- Apply updates per vendor instructions.
- Public exploit code
- Yes: 2 on Exploit-DB · 1 Metasploit module · 27 GitHub proofs of concept · 1 Nuclei template
- CISA SSVC
- exploitation active, automatable yes, technical impact totalAssessed by CISA 23 Feb 2021 (SSVC 2.0.3). Exploitation is none, poc (public proof of concept) or active.
Exploit-DB
- VMware vCenter Server 7.0 - Remote Code Execution (RCE) (Unauthenticated)webapps, 24 Jun 2021
- VMware vCenter Server 7.0 - Unauthenticated File Uploadwebapps, 1 Mar 2021
Metasploit
- exploit/multi/http/vmware_vcenter_uploadova_rceexploit, rank manual
Nuclei
- VMware vSphere Client (HTML5) - Remote Code Executiondetection template, critical
GitHub proofs of concept
- Schira4396/VcenterKiller1,484 stars
- NS-Sp4ce/CVE-2021-21972497 stars
- horizon3ai/CVE-2021-21972270 stars
- psc4re/NSE-scripts162 stars
and 23 more repositories
Listed so you can judge urgency, not as a recommendation to run anything. GitHub “proofs of concept” are unvetted: some are fake or carry malware. Exploit-DB marks the entries its staff verified.
Timeline
- 23 Feb 2021CISA SSVC assessment: exploitation active
- 24 Feb 2021First public exploit or proof of concept1 day later
- 24 Feb 2021Published1 day later
- 3 Nov 2021Added to CISA KEV (exploited in the wild)251 days (about 8 months) later
- 17 Nov 2021CISA remediation due date (US federal agencies)14 days later
- 12 Aug 2026CVE record last updated1,729 days (about 5 years) later
- 12 Nov 2026Analysed by vulneraibility.com92 days (about 3 months) later
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
| Metric | Value | What it means |
|---|---|---|
| Attack vector | NetworkReachable over the internet or any routable network. | Reachable over the internet or any routable network. |
| Attack complexity | LowRepeatable attack, no special conditions. | Repeatable attack, no special conditions. |
| Privileges required | NoneThe attacker needs no prior access. | The attacker needs no prior access. |
| User interaction | NoneNo victim action needed. | No victim action needed. |
| Scope | UnchangedImpact stays within the vulnerable component. | Impact stays within the vulnerable component. |
| Confidentiality | HighTotal data disclosure possible. | Total data disclosure possible. |
| Integrity | HighComplete modification possible. | Complete modification possible. |
| Availability | HighFull outage possible. | Full outage possible. |
Common questions
Is CVE-2021-21972 being exploited?
Yes. CVE-2021-21972 appears in CISA's Known Exploited Vulnerabilities catalog, which means exploitation in the wild has been confirmed and reported. Treat it as active rather than theoretical, and patch it ahead of higher-scoring vulnerabilities that carry no exploitation evidence.
How severe is CVE-2021-21972?
CVE-2021-21972 is rated Critical with a CVSS score of 9.8. Severity describes how bad exploitation would be, not how likely it is: pair it with exploitation evidence before deciding what to patch first.
Is there a patch for CVE-2021-21972?
Yes. A fix has been recorded for CVE-2021-21972. The vendor advisory is the authority on the exact fixed version — apply it from there rather than from a summary.
What does CVE-2021-21972 affect?
CVE-2021-21972 affects vmware:cloud_foundation, vmware:vcenter_server. Confirm the exact affected versions against the vendor advisory before deciding you are exposed.
Exploitation status reflects CISA's KEV catalog as we last synced it. Check the catalog directly.
References
5 references in the CVE record, grouped by the tags the record gives them.
Other links (5)
- vmware.com /security/advisories/VMSA-2021-0002.html
- packetstormsecurity.com /files/161590/VMware-vCenter-Server-7.0-Arbitrary-File-Upload.html
- packetstormsecurity.com /files/161695/VMware-vCenter-Server-File-Upload-Remote-Code-Execution.html
- packetstormsecurity.com /files/163268/VMware-vCenter-6.5-6.7-7.0-Remote-Code-Execution.html
- cisa.gov /known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21972
Where the data on this page comes from
- CVE List (CVE.org): description, affected versions, references; CVE Terms of Use
- NVD: CVSS and CPE data
- CISA KEV catalog: exploitation, date added, due date
- CISA Vulnrichment (ADP): SSVC decision points
- FIRST EPSS: exploit probability and percentile
- Exploit-DB: published exploits
- Metasploit Framework: exploit and scanner modules
- Nuclei templates: detection templates
- PoC-in-GitHub: GitHub repositories that claim a proof of concept
Summary, impact and triage tags: written by our AI analysis pipeline from the sources above. Check them against the sources.
Similar CVEs
Get CVEs like this by email. Join the free digest: the CVEs we flag as major, all CVSS 8.0 or higher, in up to three emails a day (sent at 05:00, 11:00 and 15:00 UTC). Matching alerts to the products you run needs an account, and accounts are invite-only during the beta.