CVE-2020-3548
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.
Key facts
- CVSS score
- 5.3 (v3.1)
- Severity
- MEDIUM
- CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L- Weakness (CWE)
- CWE-407
- EPSS score
- 0.8% (57th percentile)
- In CISA KEV
- No
- In EU EUVD
- Yes (EUVD-2020-24819)
- Published
- November 18, 2024
- NVD last modified
- June 17, 2026
- Status
- Analyzed
EU Vulnerability Database (EUVD)
This vulnerability is also tracked by ENISA as EUVD-2020-24819 in the EU Vulnerability Database. Last updated in EUVD on November 18, 2024.
View on the EU Vulnerability DatabaseAffected products
- cisco / email security appliance
Certified products that may be affected
4 FIPS 140 or Common Criteria certified products, from automated matching by sec-certs.org.
- Cisco Email Security Appliance with AsyncOS 13.0 - Cisco Systems, Inc. - Common Criteria 495-LSS - archived
- Cisco Email Security Appliance 9.8 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10798-2017 - archived
- Cisco Email Security Appliance v9.1 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10631-2015 - archived
- IronPort Email Security Appliances (ESA), comprising the C160, C370, X1060, and X1070 appliance models, running IronPort AsyncOS software, version 7.1, and the C670 appliance model running IronPort AsyncOS version 7.3 - Cisco Systems, Inc. - Common Criteria CCEVS-VR-VID-10438-2010 - archived
References
Last updated September 17, 2026 · Source: NVD, CISA KEV, FIRST.org EPSS
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