How severe is CVE-2020-3596?

CVE-2020-3596 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2020-3596 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3596?

CVE-2020-3596 primarily affects Cisco Expressway. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-3596?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.

When was CVE-2020-3596 published?

CVE-2020-3596 was published on 2020-10-08 and last updated on 2026-06-17.

CVE-2020-3596

CVE-2020-3596 is a medium-severity vulnerability in Cisco Expressway with a CVSS 3.x base score of 5.9. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-670.

Key facts

Severity: Medium (CVSS 3.x base score 5.9)
CVSS v2: 7.8
EPSS exploit prediction: 1% (65th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-670
Affected product: Cisco Expressway
Published: 2020-10-08
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2020-3596?: 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.
How severe is CVE-2020-3596?: CVE-2020-3596 has a CVSS 3.x base score of 5.9, rated medium severity. It is exploitable over network with high attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2020-3596 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (65th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3596?: CVE-2020-3596 primarily affects Cisco Expressway. In total, 2 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-3596?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-3596 published?: CVE-2020-3596 was published on 2020-10-08 and last updated on 2026-06-17.

References

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

Affected products (2)

cpe:2.3:a:cisco:expressway:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:telepresence_video_communication_server:*:*:*:*:*:*:*:*

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