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CVE-2021-40118

Cisco Cisco Adaptive Security Appliance (ASA) Software, adaptive security appliance, secure firewall threat defense

A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition. This vulnerability is due to improper input validation when parsing HTTPS requests. An attacker could exploit this vulnerability by sending a malicious HTTPS request to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

CVSS
7.5
EPSS
1.35%
69.6% 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 probability1.35%
Technical severityCVSS 7.5

Vulnerability overview

A vulnerability in the web services interface of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to trigger a denial of service (DoS) condition. This vulnerability is due to improper input validation when parsing HTTPS requests. An attacker could exploit this vulnerability by sending a malicious HTTPS request to an affected device. A successful exploit could allow the attacker to cause the device to reload, resulting in a DoS condition.

Affected product and versions

Product
Cisco Cisco Adaptive Security Appliance (ASA) Software, adaptive security appliance, secure firewall threat defense
Affected versions
< 9.8.4.40, < 6.4.0.13, >= 6.5.0 < 6.6.5, >= 6.7.0 < 6.7.0.3, >= 7.0.0 < 7.0.1, >= 9.9.0 < 9.12.4.29, >= 9.13.0 < 9.14.3.9, >= 9.15.0 < 9.15.1.17, >= 9.16.0 < 9.16.2.3, 009.012(004.024), 009.015(001), 009.015(001.015), 009.015(001.016), 009.016(001)
Fixed versions
9.8.4.40, 6.4.0.13, 6.6.5, 6.7.0.3, 7.0.1, 9.12.4.29, 9.14.3.9, 9.15.1.17, 9.16.2.3

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, adaptive security 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-121, CWE-787