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…

Browse: All 2021 CVEs · All vendors

CVSS score
5.3 Medium
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CISA KEV
Yes — actively exploited (added 2022-03-07, remediation due 2022-03-21)
Weakness (CWE)
CWE-918
Published
2021-02-24
Last modified
2026-06-17
NVD status
Analyzed

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).

Affected products

Affected ranges per NVD CPE data; confirm exact versions in the vendor advisory.

Required action (CISA)

Apply updates per vendor instructions. Federal remediation deadline: 2022-03-21.

How to prioritize this

This vulnerability is on the CISA KEV list, meaning it is being actively exploited — treat it as urgent regardless of the raw CVSS number. Use the live CVE lookup for the latest NVD data, and the CVSS 3.1 calculator to model your own environmental score. For the actively exploited vulnerabilities that matter this week, read The Exploit HQ daily security brief.

References

FAQ

Is CVE-2021-21973 actively exploited?

Yes. CISA added CVE-2021-21973 to its Known Exploited Vulnerabilities (KEV) catalog on 2022-03-07, with a federal remediation deadline of 2022-03-21. A KEV listing means real-world exploitation is confirmed, so patching this should be prioritized above many higher-CVSS bugs that aren't being exploited.

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

CVE-2021-21973 has a CVSS base score of 5.3 (Medium). Its vector string is CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N.

Related vulnerabilities

Data source: NVD & CISA KEV. Shown as-is; nothing added. Last generated from NVD data — re-check the live tool for updates.