CVE-2021-21986
The vSphere Client (HTML5) contains a vulnerability in a vSphere authentication mechanism for the Virtual SAN Health Check, Site Recovery, vSphere Lifecycle Manager, and VMware Cloud Director Availability plug-ins.
Does this matter?
EPSS puts the probability of exploitation in the next 30 days at 13.3%, higher than 96% of all known CVEs. Patch or mitigate before the next change window.
Description
The vSphere Client (HTML5) contains a vulnerability in a vSphere authentication mechanism for the Virtual SAN Health Check, Site Recovery, vSphere Lifecycle Manager, and VMware Cloud Director Availability plug-ins. A malicious actor with network access to port 443 on vCenter Server may perform actions allowed by the impacted plug-ins without authentication.
- CVSS 3.1
- 9.8 CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- EPSS
- 13.26% probability · 96th percentile
- Public exploits
- None in Exploit-DB
- CISA KEV
- Not listed
- Weakness
- CWE-306
- Affected
- vmware/vcenter server · vmware/cloud foundation
- Source
- security@vmware.com
EPSS 13.3% since 3 November 2026; no change recorded yet. The dashed line is the ten per cent mark our analysts treat as “patch before the next change window”. Points are recorded when the score first appears and whenever it moves by a percentage point or more.
References
- http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.htmlThird Party Advisory, VDB Entry
- https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlVendor Advisory
- http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.htmlThird Party Advisory, VDB Entry
- https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlVendor Advisory
Source: NVD record, EPSS from FIRST.org, KEV from CISA, exploits from Exploit-DB. Refreshed daily. Download this record as JSON.