How severe is CVE-2020-3164?

CVE-2020-3164 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.

Is CVE-2020-3164 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2020-3164?

CVE-2020-3164 primarily affects Cisco Cloud Email Security. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2020-3164?

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

When was CVE-2020-3164 published?

CVE-2020-3164 was published on 2020-03-04 and last updated on 2026-06-17.

CVE-2020-3164

CVE-2020-3164 is a medium-severity vulnerability in Cisco Cloud Email Security with a CVSS 3.x base score of 5.3. 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-20.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 1% (67th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-20
Affected product: Cisco Cloud Email Security
Published: 2020-03-04
Last modified: 2026-06-17

Description

A vulnerability in the web-based management interface of Cisco AsyncOS for Cisco Email Security Appliance (ESA), Cisco Web Security Appliance (WSA), and Cisco Content Security Management Appliance (SMA) could allow an unauthenticated remote attacker to cause high CPU usage on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of specific HTTP request headers. An attacker could exploit this vulnerability by sending a malformed HTTP request to an affected device. A successful exploit could allow the attacker to trigger a prolonged status of high CPU utilization relative to the GUI process(es). Upon successful exploitation of this vulnerability, an affected device will still be operative, but its response time and overall performance may be degraded.

Frequently asked questions

What is CVE-2020-3164?: A vulnerability in the web-based management interface of Cisco AsyncOS for Cisco Email Security Appliance (ESA), Cisco Web Security Appliance (WSA), and Cisco Content Security Management Appliance (SMA) could allow an unauthenticated remote attacker to cause high CPU usage on an affected device, resulting in a denial of service (DoS) condition. The vulnerability is due to improper validation of specific HTTP request headers. An attacker could exploit this vulnerability by sending a malformed HTTP request to an affected device. A successful exploit could allow the attacker to trigger a prolonged status of high CPU utilization relative to the GUI process(es). Upon successful exploitation of this vulnerability, an affected device will still be operative, but its response time and overall performance may be degraded.
How severe is CVE-2020-3164?: CVE-2020-3164 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability low.
Is CVE-2020-3164 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (67th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2020-3164?: CVE-2020-3164 primarily affects Cisco Cloud Email Security. In total, 4 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2020-3164?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround.
When was CVE-2020-3164 published?: CVE-2020-3164 was published on 2020-03-04 and last updated on 2026-06-17.

References

https://tools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-cont-sec-gui-dos-nJ625dXb

Affected products (4)

cpe:2.3:a:cisco:cloud_email_security:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:content_security_management_appliance:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:email_security_appliance:*:*:*:*:*:*:*:*
cpe:2.3:a:cisco:web_security_appliance:*:*:*:*:*:*:*:*

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