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CVE-2021-34781

HIGHCVSS 7.5/10EPSS 1.35%

Last modified

CVE-2021-34781 is a high-severity vulnerability rated 7.5/10 on the CVSS scale. 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. EPSS estimates a 1.35% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1
7.5/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS Probability
1.35%

67.9th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

Affected Software

VendorProductVersions
CiscoFirepower Management Center Virtual Appliance6.3.0
CiscoFirepower Management Center Virtual Appliance6.4.0
CiscoFirepower Management Center Virtual Appliance6.4.0.13
CiscoFirepower Management Center Virtual Appliance6.5.0
CiscoFirepower Management Center Virtual Appliance6.6.0
CiscoFirepower Management Center Virtual Appliance6.7.0.3
CiscoFirepower Management Center Virtual Appliance6.7.1
CiscoFirepower Management Center Virtual Appliance7.0.0
CiscoFirepower Threat Defense>= 6.3.0, < 6.4.0.13
CiscoFirepower Threat Defense>= 6.5.0, < 6.6.5
CiscoFirepower Threat Defense>= 6.7.0, < 6.7.0.3
CiscoFirepower Threat Defense>= 7.0.0, < 7.0.1
CiscoSourcefire Defense Center6.3.0
CiscoSourcefire Defense Center6.4.0
CiscoSourcefire Defense Center6.4.0.13
CiscoSourcefire Defense Center6.5.0
CiscoSourcefire Defense Center6.6.0
CiscoSourcefire Defense Center6.7.0.3
CiscoSourcefire Defense Center6.7.1
CiscoSourcefire Defense Center7.0.0

References

Timeline

Published
Last Modified
Status
Modified

Frequently Asked Questions

What is CVE-2021-34781?
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.
How severe is CVE-2021-34781?
CVE-2021-34781 has a CVSS score of 7.5/10 (HIGH severity). The EPSS model estimates a 1.35% probability of exploitation in the next 30 days.
How do I fix CVE-2021-34781?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-34781?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST