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AUSCERT External Security Bulletin Redistribution
Cisco Webex Meetings and Cisco Webex Meetings Server Host
Key Brute Forcing Vulnerability
14 January 2021
AusCERT Security Bulletin Summary
Product: Cisco Webex Meetings
Cisco Webex Meetings Server
Publisher: Cisco Systems
Operating System: Cisco
Impact/Access: Reduced Security -- Existing Account
CVE Names: CVE-2021-1311
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Cisco Webex Meetings and Cisco Webex Meetings Server Host Key Brute Forcing
Advisory ID: cisco-sa-webex-brutef-hostkey-FWRMxVF
First Published: 2021 January 13 16:00 GMT
Version 1.0: Final
Workarounds: No workarounds available
Cisco Bug IDs: CSCvv72420 CSCvv84319
CVE Names: CVE-2021-1311
o A vulnerability in the reclaim host role feature of Cisco Webex Meetings
and Cisco Webex Meetings Server could allow an authenticated, remote
attacker to take over the host role during a meeting.
This vulnerability is due to a lack of protection against brute forcing of
the host key. An attacker could exploit this vulnerability by sending
crafted requests to a vulnerable Cisco Webex Meetings or Webex Meetings
Server site. A successful exploit would require the attacker to have access
to join a Webex meeting, including applicable meeting join links and
passwords. A successful exploit could allow the attacker to acquire or take
over the host role for a meeting.
Cisco has released software updates that address this vulnerability. There
are no workarounds that address this vulnerability.
This advisory is available at the following link:
o Vulnerable Products
This vulnerability affected all Cisco Webex Meetings sites prior to
December 15, 2020. Webex Meetings is cloud based.
At the time of publication, this vulnerability also affected the following
releases of Cisco Webex Meetings Server, which is on premises. See the
Details section in the bug ID(s) at the top of this advisory for the most
complete and current information.
3.0MR3 Security Patch 5 and earlier
4.0MR3 Security Patch 4 and earlier
Products Confirmed Not Vulnerable
Only products listed in the Vulnerable Products section of this advisory
are known to be affected by this vulnerability.
o There are no workarounds that address this vulnerability.
o When considering software upgrades , customers are advised to regularly
consult the advisories for Cisco products, which are available from the
Cisco Security Advisories page , to determine exposure and a complete
In all cases, customers should ensure that the devices to be upgraded
contain sufficient memory and confirm that current hardware and software
configurations will continue to be supported properly by the new release.
If the information is not clear, customers are advised to contact the Cisco
Technical Assistance Center (TAC) or their contracted maintenance
Cisco has addressed this vulnerability in Cisco Webex Meetings sites, which
are cloud based. No user action is required.
At the time of publication, the following releases for Cisco Webex Meetings
Server, which is on-premises software, contained the fix for this
vulnerability. Customers are advised to apply updated software releases.
See the Details section in the bug ID(s) at the top of this advisory for
the most complete and current information.
3.0MR3 Security Patch 6
4.0MR3 Security Patch 5
Customers who need additional information are advised to contact the Cisco
TAC or their contracted maintenance providers.
Exploitation and Public Announcements
o The Cisco Product Security Incident Response Team (PSIRT) is not aware of
any public announcements or malicious use of the vulnerability that is
described in this advisory.
o Cisco would like to thank Nabeel Ahmed and Tom Wyckhuys of NTT Belgium for
reporting this vulnerability.
Cisco Security Vulnerability Policy
o To learn about Cisco security vulnerability disclosure policies and
publications, see the Security Vulnerability Policy . This document also
contains instructions for obtaining fixed software and receiving security
vulnerability information from Cisco.
| Version | Description | Section | Status | Date |
| 1.0 | Initial public release. | - | Final | 2021-JAN-13 |
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