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CVE-2021-34793

HIGH CVSS: 8.6 Published: 2021-10-27 Modified: 2026-08-11

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.

Affected Platforms

Cisco Asa 5585-XCisco Asa 5525-XCisco Secure Firewall Threat DefenseCisco Adaptive Security Appliance SoftwareCisco Asa 5515-XCisco Asa 5545-X FirmwareCisco Asa 5585-X FirmwareCisco Asa 5512-X FirmwareCisco Adaptive Security ApplianceCisco Asa 5580 Firmware

Weakness Type

CWE-924, CWE-924

References