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CVE-2021-34793

8.6 · HIGH

A vulnerability in the TCP Normalizer of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software operating in transparent mode could allow an unauthenticated, r…

Published Oct 27, 2021CWE-924EPSS 0.59%

Overview

CVE-2021-34793 is a high-severity vulnerability. It was published on October 27, 2021 and has a CVSS 3.1 base score of 8.6 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

A vulnerability in the TCP Normalizer of Cisco Adaptive Security Appliance (ASA) Software and Firepower Threat Defense (FTD) Software operating in transparent mode could allow an unauthenticated, remote attacker to poison MAC address tables, resulting in a denial of service (DoS) vulnerability. This vulnerability is due to incorrect handling of certain TCP segments when the affected device is operating in transparent mode. An attacker could exploit this vulnerability by sending a crafted TCP segment through an affected device. A successful exploit could allow the attacker to poison the MAC address tables in adjacent devices, resulting in network disruption.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

Reftools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-dos-JxYWMJyLReftools.cisco.com/security/center/content/CiscoSecurityAdvisory/cisco-sa-asa-ftd-dos-JxYWMJyL

How CyberStrike helps

Frequently asked questions

What is CVE-2021-34793?

CVE-2021-34793 is a high-severity vulnerability. It was published on October 27, 2021 and has a CVSS 3.1 base score of 8.6 (HIGH).

How severe is CVE-2021-34793?

This vulnerability has a CVSS 3.1 base score of 8.6, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2021-34793?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2021-34793?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2021-34793 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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