CVE-2021-34793
Cisco Adaptive Security Appliance
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.
Exploitation status
- A vendor advisory or patch reference has been published.
What the metrics mean
- It is reachable over a network, without needing local access.
- For an attacker who can reach it, no special conditions are needed to exploit it.
- To exploit it, no account is needed.
- Beyond that, no action by a user is required.
Scoring
- CVSS
- 8.6 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H- Weakness
- CWE-924
- Assigned by
- psirt@cisco.com
Dates
- Published
- 2021-10-27
- Last modified
- 2026-08-11
- Sources
- NVD
Affected products
- Cisco Adaptive Security Appliance- 9.8.4.40
- Cisco Secure Firewall Threat Defense- 6.4.0.13, 6.5.0 - 6.6.5, 6.7.0 - 6.7.0.3
- Cisco Adaptive Security Appliance Software9.9.0 - 9.12.4.29, 9.13.0 - 9.14.3.9, 9.15.0 - 9.15.1.17, 9.16.0 - 9.16.2.3
- Cisco Asa 5512-X Firmware009.008\(004.025\)
- Cisco Asa 5512-Xall versions
- Cisco Asa 5505 Firmware009.008\(004.025\)
- Cisco Asa 5505all versions
- Cisco Asa 5515-X Firmware009.008\(004.025\)
- Cisco Asa 5515-Xall versions
- Cisco Asa 5525-X Firmware009.008\(004.025\)
- Cisco Asa 5525-Xall versions
- Cisco Asa 5545-X Firmware009.008\(004.025\)
As listed in the NVD configuration data. Not a statement about your estate.