Exploited

CVE-2021-21973

VMware (Broadcom) vCenter Server · Virtualization, VDI and cloud

VMware vCenter Server and Cloud Foundation Server Side Request Forgery (SSRF) Vulnerability

At a glance

Exploited. Added to CISA’s catalog of exploited vulnerabilities on March 7, 2022.

Affected product: VMware (Broadcom) vCenter Server (category Virtualization, VDI and cloud, indicative classification). Name in CISA’s catalog: VMware vCenter Server and Cloud Foundation.

What should I do?

Apply the security update from VMware (Broadcom).

Deadline set by CISA for US federal agencies: 14 days (due March 21, 2022). It only binds those agencies, but it is a useful measure of urgency.

VMware (Broadcom) security advisories page (general page, not the advisory for this vulnerability)
The vendor’s specific advisory is listed in the NVD references: CVE-2021-21973 on the NVD website.

Original text of the required action (CISA)

Apply updates per vendor instructions.

Timeline

February 24, 2021 Vulnerability published Publication date (NVD)
March 7, 2022 Exploitation confirmed Added to CISA’s KEV catalog
March 21, 2022 CISA deadline Remediation deadline set for US federal agencies

The facts, with their sources

Exploitation confirmed: Yes, on March 7, 2022 Date added to the catalog of exploited vulnerabilities. Exploitation itself may have started earlier. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Ransomware: No known use to date That does not guarantee it is not being used: the information is not public. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Hunt for compromise: Not requested by CISA Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA required action: Apply the security update from VMware (Broadcom). Rewritten by this site from CISA’s original text. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CISA deadline: March 21, 2022, 14 days Set for US federal agencies: a measure of urgency, not an obligation elsewhere. Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
Vulnerability published: February 24, 2021 Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC
Product according to CISA: VMware vCenter Server and Cloud Foundation Filed by this site under “Virtualization, VDI and cloud” (indicative classification). Source: KEV catalog, collected September 29, 2026 at 14:57 UTC
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N Technical detail of the score: attack vector, complexity, impact. Source: National Vulnerability Database (NVD), collected September 29, 2026 at 15:00 UTC

Severity and activity

5.3 / 10 CVSS severity: medium

Score from the NVD. Collected Sep 29, 2026.

— Probability of exploitation in the next 30 days (EPSS)

FIRST’s EPSS model. Since exploitation is already confirmed, this figure is mostly useful to compare activity. Collected Sep 29, 2026.

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).

VMware vCenter Server and Cloud Foundation Server contain a SSRF vulnerability due to improper validation of URLs in a vCenter Server plugin. This allows for information disclosure.

Summary from CISA (KEV catalog).

CERT-FR advisories

No advisory among the latest CERT-FR publications this site follows. That does not mean there are none.

Information reused under the Open Licence 2.0 (Etalab); the date of last update is shown for each advisory. This site is neither affiliated with nor endorsed by ANSSI.

Sources for this page

CISA KEV catalog: exploitation, date added, required action, deadline, ransomware.
NVD (NIST): CVSS severity, publication date, description, vendor references.
EPSS (FIRST): probability of exploitation.
CERT-FR: advisories and alerts (in French).
Brand and category: indicative classification by this site (method).