VULNERABILITY INTELLIGENCE

CVE-2021-34781

CVSS score8.6 HIGH
EPSS probability1.40%
CISA KEVNot currently listed
Published2021-10-27
Last modified2026-08-11
CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

Description

A vulnerability in the processing of SSH connections for multi-instance deployments of Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on the affected device. This vulnerability is due to a lack of proper error handling when an SSH session fails to be established. An attacker could exploit this vulnerability by sending a high rate of crafted SSH connections to the instance. A successful exploit could allow the attacker to cause resource exhaustion, which causes a DoS condition on the affected device. The device must be manually reloaded to recover.

Weakness classification

  • psirt@cisco.com: CWE-119
  • nvd@nist.gov: CWE-755

Primary references