Is CVE-2020-3548 in the CISA KEV catalog?

No. CVE-2020-3548 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2020-3548?

CVE-2020-3548 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2020-3548?

CVE-2020-3548 has an EPSS score of 0.81% (52th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix or mitigate CVE-2020-3548?

No published fix for CVE-2020-3548 has been found yet. Check the linked vendor advisories for guidance as it becomes available.

CVE & CISA-KEV Catalog

CVE-2020-3548

MEDIUM

5.3

CVSS v3

NVD

Description

A vulnerability in the Transport Layer Security (TLS) protocol implementation of Cisco AsyncOS software for Cisco Email Security Appliance (ESA) 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 inefficient processing of incoming TLS traffic. An attacker could exploit this vulnerability by sending a series of crafted TLS packets to an affected device. A successful exploit could allow the attacker to trigger a prolonged state of high CPU utilization. The affected device would still be operative, but response time and overall performance may be degraded.There are no workarounds that address this vulnerability.

CWE-407

How to fix

No published remediation has been found for this vulnerability's affected products yet.

Mitigation guidance may be in the linked vendor advisories in the References section below.

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityNone

IntegrityNone

AvailabilityLow

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

Exploit Intelligence

0.81%probability of exploitation in 30 days

52ndpercentile

Moderate risk: more likely to be exploited than 52% of all known CVEs.

References

Vendor Advisory1

sec.cloudapps.cisco.com

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-07-31.