CVE-2020-3419: Cisco Webex Meetings and Cisco Webex Meetings Server Ghost Join Vulnerability

Severity: critical (CVSS 9.1 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 1.8% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2020-11-18 · updated 2026-06-17
Weakness: CWE-913

Description

A vulnerability in Cisco Webex Meetings and Cisco Webex Meetings Server could allow an unauthenticated, remote attacker to join a Webex session without appearing on the participant list. This vulnerability is due to improper handling of authentication tokens by a vulnerable Webex site. An attacker could exploit this vulnerability by sending crafted requests to a vulnerable Cisco Webex Meetings or Cisco Webex Meetings Server site. A successful exploit requires the attacker to have access to join a Webex meeting, including applicable meeting join links and passwords. The attacker could then exploit this vulnerability to join meetings, without appearing in the participant list, while having full access to audio, video, chat, and screen sharing capabilities.

Affected products

Cisco WebEx Meetings Server: before 3.0; 3.0, 3.0-maintenance_release2, 3.0-maintenance_release3, 4.0, 4.0-maintenance_release1, 4.0-maintenance_release2 — fixed in 3.0

How to fix

Upgrade to a fixed version: Cisco WebEx Meetings Server 3.0. Check the vendor advisory for mitigations.

References

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