CVE-2021-34793

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.

• cisco adaptive security appliance (< 9.8.4.40) • cisco secure firewall threat defense (< 6.4.0.13) • cisco secure firewall threat defense (>= 6.5.0 < 6.6.5) • cisco secure firewall threat defense (>= 6.7.0 < 6.7.0.3) • cisco adaptive security appliance software (>= 9.9.0 < 9.12.4.29) • cisco adaptive security appliance software (>= 9.13.0 < 9.14.3.9) • cisco adaptive security appliance software (>= 9.15.0 < 9.15.1.17) • cisco adaptive security appliance software (>= 9.16.0 < 9.16.2.3) • cisco asa 5512-x firmware 009.008\(004.025\) • cisco asa 5505 firmware 009.008\(004.025\) • cisco asa 5515-x firmware 009.008\(004.025\) • cisco asa 5525-x firmware 009.008\(004.025\) • cisco asa 5545-x firmware 009.008\(004.025\) • cisco asa 5555-x firmware 009.008\(004.025\) • cisco asa 5580 firmware 009.008\(004.025\) • cisco asa 5585-x firmware 009.008\(004.025\)