UpHeron
All vulnerabilities

Servers and applications

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…

Severity
High 8.6
Published
27 Oct 2021
Last changed
11 Aug 2026
Added to UpHeron
1 Nov 2026
Fixed in
9.8.4.40, 9.12.4.29, 9.14.3.9, 9.15.1.17, 9.16.2.3
Sources
NVD

Affected software

SoftwareAffected versions
Cisco ASA and Firepower Threat DefenseServers and applications · cpe:a:cisco:adaptive_security_appliance
  • Every version before 9.8.4.40
Cisco ASA and Firepower Threat DefenseServers and applications · cpe:o:cisco:adaptive_security_appliance_software
  • From 9.9.0 before 9.12.4.29
  • From 9.13.0 before 9.14.3.9
  • From 9.15.0 before 9.15.1.17
  • From 9.16.0 before 9.16.2.3

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2021-34793
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2021-34793