CVE-2021-34781 Cisco Firepower Threat Defense Software SSH Connections Denial of Service Vulnerability
Unauthenticated remote attackers can cause denial of service on Cisco FTD devices by exhausting resources via crafted SSH connections in multi-instance deployments.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- None listed
What is CVE-2021-34781?
CVE-2021-34781 is a high-severity denial of service vulnerability in Cisco Secure Firewall Threat Defense, published on 27 Oct 2021. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official 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.
Which versions are affected by CVE-2021-34781?
It affects 3 products.
Products include Cisco Firepower Management Center Virtual Appliance, Cisco Secure Firewall Threat Defense, Cisco Sourcefire Defense Center.
How do I fix CVE-2021-34781?
No fix has been published for CVE-2021-34781 yet. Limit exposure of the affected software until one is available.
Upgrade, then put limits on request size, rate and nesting depth so one client cannot exhaust the service. More about Denial of service.
Is CVE-2021-34781 being exploited?
There is no known exploitation of CVE-2021-34781 in the wild and no public exploit code.
Other vulnerabilities in Cisco Secure Firewall Threat Defense
- CVE-2021-34762 Cisco Firepower Management Center Software Authenticated Directory Traversal Vulnerability
- CVE-2021-34755 Cisco Firepower Threat Defense Software Command Injection Vulnerabilities
- CVE-2021-34756 Cisco Firepower Threat Defense Software Command Injection Vulnerabilities
- CVE-2021-34763 Cisco Firepower Management Center Software Cross-Site Scripting and Open Redirect Vulnerabilities
- CVE-2021-34764 Cisco Firepower Management Center Software Cross-Site Scripting and Open Redirect Vulnerabilities
Sources
Also known as GHSA-cg69-5r4f-47q5.