What’s Vulnerable › Vulnerabilities

CVE-2020-3596: Cisco Expressway Series and TelePresence Video Communication Server Denial of Service Vulnerability

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.2% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2020-10-08 · updated 2026-06-17
• Weakness: CWE-789

Description

A vulnerability in the Session Initiation Protocol (SIP) of Cisco Expressway Series and Cisco TelePresence Video Communication Server (VCS) could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. The vulnerability is due to incorrect handling of incoming SIP traffic. An attacker could exploit this vulnerability by sending a series of SIP packets to an affected device. A successful exploit could allow the attacker to exhaust memory on an affected device, causing it to crash and leading to a DoS condition.

Affected products

• Cisco Expressway: through x12.6.3
• Cisco TelePresence Video Communication Server (VCS) Expressway: through x12.6.3

References

• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-expressway-vcs-dos-n6xxTMZB
• https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-expressway-vcs-dos-n6xxTMZB

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