Exploited vulnerability · CISA KEV

Is CVE-2021-21985 exploited? Yes: in CISA KEV since 3 Nov 2021

Gociux · VMware vCenter Server · data: CISA KEV, CVE record, FIRST EPSS

Yes. CVE-2021-21985, VMware vCenter Server Improper Input Validation Vulnerability, is being exploited in the wild. CISA added it to its Known Exploited Vulnerabilities catalog on 3 Nov 2021, 161 days after it was published. It is known to be used in ransomware campaigns. It affects VMware vCenter Server. If you run it, CISA's required action is: Apply updates per vendor instructions.

exploitedYesCISA KEV · 3 Nov 2021

ransomwareKnownused in campaigns

EPSStop 1%among the most likely CVEs to be exploited

severity9.8CVSS 3.1 · critical

US federal due17 Nov 2021BOD 22-01 deadline

What it is

VMware vSphere Client contains an improper input validation vulnerability in the Virtual SAN Health Check plug-in, which is enabled by default in vCenter Server, which allows for remote code execution.

Vendor	VMware (26 exploited CVEs in KEV)
Product	vCenter Server
Vulnerability	VMware vCenter Server Improper Input Validation Vulnerability
Weakness	CWE-20, CWE-470, CWE-918
Published	26 May 2021
Added to KEV	3 Nov 2021
Reported by (CNA)	vmware

What to do

Check whether you run it. Look for vCenter Server in your asset inventory, including appliances and cloud images. Stack check lists every exploited VMware CVE at once.
Apply the fix. Apply updates per vendor instructions.
If you can't patch today, take the affected service off the internet or restrict who can reach it, and check its logs for signs of compromise since 26 May 2021.
Get told next time. Email alerts when CISA adds a CVE for VMware.

Other exploited CVEs in vCenter Server

CVE-2024-38813: VMware vCenter Server Privilege Escalation Vulnerability (20 Nov 2024)
CVE-2024-38812: VMware vCenter Server Heap-Based Buffer Overflow Vulnerability (20 Nov 2024)
CVE-2022-22948: VMware vCenter Server Incorrect Default File Permissions Vulnerability (17 Jul 2024)
CVE-2023-34048: VMware vCenter Server Out-of-Bounds Write Vulnerability (22 Jan 2024)
CVE-2021-22017: VMware vCenter Server Improper Access Control (10 Jan 2022)
CVE-2021-22005: VMware vCenter Server File Upload Vulnerability (3 Nov 2021)

References

nvd.nist.gov/vuln/detail/CVE-2021-21985

Questions

Is CVE-2021-21985 being exploited?

Yes. CISA added CVE-2021-21985 to the Known Exploited Vulnerabilities catalog on 3 Nov 2021, which means there is reliable evidence of exploitation in the wild.

Is CVE-2021-21985 used in ransomware attacks?

Yes, CISA lists it as known to be used in ransomware campaigns.

How do I fix CVE-2021-21985?

Apply updates per vendor instructions. Check VMware's advisory for the fixed versions, and if you can't patch quickly, restrict access to the affected vCenter Server and watch it for signs of compromise.

Sources: CISA KEV (exploitation, ransomware use, required action, due date), the CVE record (publication date, CVSS, CNA), NVD and FIRST EPSS (live score). More: all KEV additions in November 2021 · VMware scorecard · act-now radar.

Running VMware in a regulated environment?

We check exposure across your estate, patch or mitigate with your team, and set up detection for what attackers do after exploiting it.

Get in touch →