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AUSCERT External Security Bulletin Redistribution
ESB-2021.2387.2
VMWare Multiple Vulnerabilities
30 August 2021
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AusCERT Security Bulletin Summary
---------------------------------
Product: VMware ESXi
VMware Cloud Foundation
Publisher: VMware
Operating System: Virtualisation
VMware ESX Server
Impact/Access: Provide Misleading Information -- Existing Account
Denial of Service -- Remote/Unauthenticated
Resolution: Patch/Upgrade
CVE Names: CVE-2021-21995 CVE-2021-21994
Original Bulletin:
https://www.vmware.com/security/advisories/VMSA-2021-0014.html
Revision History: August 30 2021: Vendor updated fixed version details
July 14 2021: Initial Release
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Advisory ID: VMSA-2021-0014.1
CVSSv3 Range: 5.3-7.0
Issue Date: 2021-07-13
Updated On: 2021-08-24
CVE(s): CVE-2021-21994, CVE-2021-21995
Synopsis: VMware ESXi updates address authentication and denial of service
vulnerabilities (CVE-2021-21994, CVE-2021-21995)
1. Impacted Products
o VMware ESXi
o VMware Cloud Foundation (Cloud Foundation)
2. Introduction
Multiple vulnerabilities in VMware ESXi were privately reported to VMware.
Updates and workarounds are available to remediate these vulnerabilities in
affected VMware products.
3a. ESXi SFCB improper authentication vulnerability (CVE-2021-21994)
Description
SFCB (Small Footprint CIM Broker) as used in ESXi has an authentication bypass
vulnerability.VMware has evaluated the severity of this issue to be in the
Important severity range with a maximum CVSSv3 base score of 7.0.
Known Attack Vectors
A malicious actor with network access to port 5989 on ESXi may exploit this
issue to bypass SFCB authentication by sending a specially crafted request.
Resolution
To remediate CVE-2021-21994 apply the patches listed in the 'Fixed Version'
column of the 'Response Matrix' found below.
Workarounds
Workarounds for CVE-2021-21994 have been listed in the 'Workarounds' column of
the 'Response Matrix' below.
Additional Documentation
None.
Notes
SFCB service is not enabled by default on ESXi. For successful exploitation,
SFCB service should be running. The status of the service can be checked by
following the steps mentioned in KB1025757.
Acknowledgements
VMware would like to thank Douglas Everson of Voya Financial for reporting this
issue to us.
Response Matrix
Product Version Running CVE Identifier CVSSv3 Severity Fixed Version Workarounds Additional
On Documentation
ESXi 7.0 Any CVE-2021-21994 7.0 important ESXi70U2-17630552 KB1025757 None
ESXi 6.7 Any CVE-2021-21994 7.0 important ESXi670-202103101-SG KB1025757 None
ESXi 6.5 Any CVE-2021-21994 7.0 important ESXi650-202107401-SG KB1025757 None
Impacted Product Suites that Deploy Response Matrix 3a Components:
Product Version Running CVE Identifier CVSSv3 Severity Fixed Workarounds Additional
On Version Documentation
Cloud
Foundation 4.x Any CVE-2021-21994 7.0 important 4.3 KB1025757 None
(ESXi)
Cloud
Foundation 3.x Any CVE-2021-21994 7.0 important 3.10.2 KB1025757 None
(ESXi)
3b. ESXi OpenSLP denial-of-service vulnerability (CVE-2021-21995)
Description
OpenSLP as used in ESXi has a denial-of-service vulnerability due a heap
out-of-bounds read issue. VMware has evaluated the severity of this issue to be
in the Moderate severity range with a maximum CVSSv3 base score of 5.3.
Known Attack Vectors
A malicious actor with network access to port 427 on ESXi may be able to
trigger a heap out-of-bounds read in OpenSLP service resulting in a
denial-of-service condition.
Resolution
To remediate CVE-2021-21995 apply the patches listed in the 'Fixed Version'
column of the 'Response Matrix' found below.
Workarounds
Workarounds for CVE-2021-21995 have been listed in the 'Workarounds' column of
the 'Response Matrix' below.
Additional Documentation
None.
Notes
Per the Security Configuration Guides for VMware vSphere, VMware now recommends
disabling the OpenSLP service in ESXi if it is not used. For more information,
see our blog posting: https://blogs.vmware.com/vsphere/2021/02/
evolving-the-vmware-vsphere-security-configuration-guides.html
Acknowledgements
VMware would like to thank VictorV(Tangtianwen) of Kunlun Lab for reporting
this issue to us.
Response Matrix
Product Version Running CVE Identifier CVSSv3 Severity Fixed Version Workarounds Additional
On Documentation
ESXi 7.0 Any CVE-2021-21995 5.3 moderate ESXi70U2-17630552 KB76372 None
ESXi 6.7 Any CVE-2021-21995 5.3 moderate ESXi670-202103101-SG KB76372 None
ESXi 6.5 Any CVE-2021-21995 5.3 moderate ESXi650-202107401-SG KB76372 None
Impacted Product Suites that Deploy Response Matrix 3b Components:
Product Version Running CVE Identifier CVSSv3 Severity Fixed Workarounds Additional
On Version Documentation
Cloud
Foundation 4.x Any CVE-2021-21995 5.3 moderate 4.3 KB76372 None
(ESXi)
Cloud
Foundation 3.x Any CVE-2021-21995 5.3 moderate 3.10.2 KB76372 None
(ESXi)
4. References
VMware ESXi 7.0 ESXi70U2-17630552
Downloads and Documentation:
https://my.vmware.com/group/vmware/patch
https://docs.vmware.com/en/VMware-vSphere/7.0/rn/
vsphere-esxi-702-release-notes.html
VMware ESXi 6.7 ESXi670-202103101-SG
Downloads and Documentation:
https://my.vmware.com/group/vmware/patch
https://docs.vmware.com/en/VMware-vSphere/6.7/rn/esxi670-202103001.html
VMware ESXi 6.5 ESXi650-202107401-SG
Downloads and Documentation:
https://my.vmware.com/group/vmware/patch
https://docs.vmware.com/en/VMware-vSphere/6.5/rn/esxi650-202107001.html
VMware Cloud Foundation 4.3
Downloads and Documentation:
https://docs.vmware.com/en/VMware-Cloud-Foundation/4.3/rn/
VMware-Cloud-Foundation-43-Release-Notes.html
VMware Cloud Foundation 3.10.2
Downloads and Documentation:
https://docs.vmware.com/en/VMware-Cloud-Foundation/3.10.2/rn/
VMware-Cloud-Foundation-3102-Release-Notes.html
Mitre CVE Dictionary Links:
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21994
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-21995
FIRST CVSSv3 Calculator:
CVE-2021-21994: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:H/
PR:N/UI:N/S:U/C:H/I:L/A:L
CVE-2021-21995: https://www.first.org/cvss/calculator/3.1#CVSS:3.1/AV:N/AC:L/
PR:N/UI:N/S:U/C:N/I:N/A:L
5. Change Log
2021-07-13 VMSA-2021-0014
Initial security advisory.
2021-08-24 VMSA-2021-0014.1
Added Cloud Foundation 4.x fixed version in the Response Matrix section of 3a
and 3b.
6. Contact
E-mail list for product security notifications and announcements:
https://lists.vmware.com/mailman/listinfo/security-announce
This Security Advisory is posted to the following lists:
security-announce@lists.vmware.com
bugtraq@securityfocus.com
fulldisclosure@seclists.org
E-mail: security@vmware.com
PGP key at:
https://kb.vmware.com/kb/1055
VMware Security Advisories
https://www.vmware.com/security/advisories
VMware Security Response Policy
https://www.vmware.com/support/policies/security_response.html
VMware Lifecycle Support Phases
https://www.vmware.com/support/policies/lifecycle.html
VMware Security & Compliance Blog
https://blogs.vmware.com/security
Twitter
https://twitter.com/VMwareSRC
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