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CVE-2021-34781

Cisco Cisco Adaptive Security Appliance (ASA) Software, firepower management center virtual appliance, secure firewall threat defense

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....

CVSS
7.5
EPSS
1.39%
70.5% percentile
CISA KEV
Not listed
Published
2021.10.28
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability1.39%
Technical severityCVSS 7.5

Vulnerability overview

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....

Affected product and versions

Product
Cisco Cisco Adaptive Security Appliance (ASA) Software, firepower management center virtual appliance, secure firewall threat defense
Affected versions
6.3.0, 6.4.0, 6.4.0.13, 6.5.0, 6.6.0, 6.7.0.3, 6.7.1, 7.0.0, >= 6.3.0 < 6.4.0.13, >= 6.5.0 < 6.6.5, >= 6.7.0 < 6.7.0.3, >= 7.0.0 < 7.0.1
Fixed versions
6.4.0.13, 6.6.5, 6.7.0.3, 7.0.1

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
  1. 1
    Identify

    Confirm that Cisco Cisco Adaptive Security Appliance (ASA) Software, firepower management center virtual appliance, secure firewall threat defense and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CWE
CWE-119, CWE-755