CVE-2021-34781 Vulnerability Analysis & Exploit Details

CVE-2021-34781
Vulnerability Scoring

8.6
/10
Severe Risk

Cybersecurity professionals consider CVE-2021-34781 an immediate threat requiring urgent mitigation.

Attack Complexity Details

  • Attack Complexity: Low
    Exploits can be performed without significant complexity or special conditions.
  • Attack Vector: Network
    Vulnerability is exploitable over a network without physical access.
  • Privileges Required: None
    No privileges are required for exploitation.
  • Scope: Changed
    Successful exploitation can impact components beyond the vulnerable component.
  • User Interaction: None
    No user interaction is necessary for exploitation.

CVE-2021-34781 Details

Status: Modified

Last updated: 🕕 21 Nov 2024, 06:11 UTC
Originally published on: 🕖 27 Oct 2021, 19:15 UTC

Time between publication and last update: 1120 days

CVSS Release: version 3

CVSS3 Source

ykramarz@cisco.com

CVSS3 Type

Secondary

CVSS3 Vector

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

CVE-2021-34781 Vulnerability Summary

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.

Assessing the Risk of CVE-2021-34781

Access Complexity Graph

The exploitability of CVE-2021-34781 depends on two key factors: attack complexity (the level of effort required to execute an exploit) and privileges required (the access level an attacker needs).

Exploitability Analysis for CVE-2021-34781

With low attack complexity and no required privileges, CVE-2021-34781 is an easy target for cybercriminals. Organizations should prioritize immediate mitigation measures to prevent unauthorized access and data breaches.

Understanding AC and PR

A lower complexity and fewer privilege requirements make exploitation easier. Security teams should evaluate these aspects to determine the urgency of mitigation strategies, such as patch management and access control policies.

Attack Complexity (AC) measures the difficulty in executing an exploit. A high AC means that specific conditions must be met, making an attack more challenging, while a low AC means the vulnerability can be exploited with minimal effort.

Privileges Required (PR) determine the level of system access necessary for an attack. Vulnerabilities requiring no privileges are more accessible to attackers, whereas high privilege requirements limit exploitation to authorized users with elevated access.

CVSS Score Breakdown Chart

Above is the CVSS Sub-score Breakdown for CVE-2021-34781, illustrating how Base, Impact, and Exploitability factors combine to form the overall severity rating. A higher sub-score typically indicates a more severe or easier-to-exploit vulnerability.

CIA Impact Analysis

Below is the Impact Analysis for CVE-2021-34781, showing how Confidentiality, Integrity, and Availability might be affected if the vulnerability is exploited. Higher values usually signal greater potential damage.

  • Confidentiality: None
    CVE-2021-34781 has no significant impact on data confidentiality.
  • Integrity: None
    CVE-2021-34781 poses no threat to data integrity.
  • Availability: High
    CVE-2021-34781 can disrupt system operations, potentially causing complete denial of service (DoS).

Exploit Prediction Scoring System (EPSS)

The EPSS score estimates the probability that this vulnerability will be exploited in the near future.

EPSS Score: 0.159% (probability of exploit)

EPSS Percentile: 53.82% (lower percentile = lower relative risk)
This vulnerability is less risky than approximately 46.18% of others.

CVE-2021-34781 References

External References

CWE Common Weakness Enumeration

CWE-755

Vulnerable Configurations

  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0.13:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.4.0.13:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.5.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.6.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:6.7.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_management_center_virtual_appliance:7.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.4:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.5:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.5:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.6:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.3.0.6:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.4:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.5:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.5:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.6:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.6:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.7:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.7:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.8:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.8:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.9:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.9:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.10:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.10:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.11:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.11:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.12:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.4.0.12:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.5.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.4:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.4:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.5:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.5.0.5:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.6.4:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.6.4:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.7.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.7.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.2:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:6.7.0.2:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:7.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:7.0.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:firepower_threat_defense:7.0.0.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:firepower_threat_defense:7.0.0.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.3.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.3.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0.13:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.4.0.13:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.5.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.5.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.6.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.6.0:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0.3:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.7.0.3:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:6.7.1:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:6.7.1:*:*:*:*:*:*:*
  • cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:*
    cpe:2.3:a:cisco:sourcefire_defense_center:7.0.0:*:*:*:*:*:*:*

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