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Vulnerabilities

Vulnerability · CVE-2021-21991

The vCenter Server contains a local privilege escalation vulnerability due to the way it handles session tokens.

Published Sep 22, 2021 · catalog updated Jun 17, 2026 · cloud foundation

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2021-21991. EPSS is 0.32%. Act only if a listed version of cloud foundation is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
High7.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.32%
Remediation
Version ranges on file
Affected products
cpe vmware/cloud foundation · cpe vmware/vcenter server

The vCenter Server contains a local privilege escalation vulnerability due to the way it handles session tokens. A malicious actor with non-administrative user access on vCenter Server host may exploit this issue to escalate privileges to Administrator on the vSphere Client (HTML5) or vCenter Server vSphere Web Client (FLEX/Flash).

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe vmware/cloud foundation< 3.10.2.2
  • cpe vmware/cloud foundation< 4.3
  • cpe vmware/vcenter server6.5

How to fix CVE-2021-21991

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-21991. EPSS is 0.32%. Act only if a listed version of cloud foundation is installed.

Which versions are affected?

Compare what you have installed with vmware/cloud foundation < 3.10.2.2; vmware/cloud foundation < 4.3; vmware/vcenter server 6.5. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.32%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

VMware security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Sep 22, 2021 · Monitored products — critical

    Detected

    The vCenter Server contains a local privilege escalation vulnerability due to the way it handles session tokens. A malicious actor with non-administrative user access on vCenter Server host may exploit this issue to escalate privileges to Administrator on the vSphere Client (HTML5) or vCenter Server vSphere Web Client (FLEX/Flash).

  2. Jun 17, 2026 · Monitored products — critical

    Updated

    The vCenter Server contains a local privilege escalation vulnerability due to the way it handles session tokens. A malicious actor with non-administrative user access on vCenter Server host may exploit this issue to escalate privileges to Administrator on the vSphere Client (HTML5) or vCenter Server vSphere Web Client (FLEX/Flash).

Sources

  • CVE.orgVulnerability recordCVE-2021-21991

    Official CVE identifier

    cve.org
  • Monitored products — criticalVendor advisoryCVE-2021-21991

    The vCenter Server contains a local privilege escalation vulnerability due to the way it handles session tokens. A malicious actor with non-administrative user access on vCenter Server host may exploit this issue to escalate privileges to Administrator on the vSphere Client (HTML5) or vCenter Server vSphere Web Client (FLEX/Flash).

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Monitored products — criticalNov 6, 2026
  • CVE.orgNov 2, 2026