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Vulnerability record · CVE-2020-3596 · published 8 October 2020

CVE-2020-3596: Cisco expressway vulnerability

Cisco · Expressway

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.

7.5 CVSS 3.1 High EPSS 1.2% · top 32.3% CWE-789 · CWE-789CWE-670 · CWE-670
7.5CVSS 3.1 base score, v2 7.8
1.2%EPSS exploitation probability, 30 days
NoNot in CISA KEV
2Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

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.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

2 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

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

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2020-3596), CISA KEV, FIRST EPSS (scores of 2026-09-29). This page is refreshed as NVD updates the record.