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ReviewHigh

CVE-2021-40117

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

A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected device to reload, resulting in a DoS condition.

CVSS
7.5
EPSS
1.53%
73.0% 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 probability1.53%
Technical severityCVSS 7.5

Vulnerability overview

A vulnerability in SSL/TLS message handler for Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software could allow an unauthenticated, remote attacker to cause a denial of service (DoS) condition on an affected device. This vulnerability exists because incoming SSL/TLS packets are not properly processed. An attacker could exploit this vulnerability by sending a crafted SSL/TLS packet to an affected device. A successful exploit could allow the attacker to cause the affected 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, < 6.2.3.17, >= 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, >= 9.9.0 < 9.12.4.26, >= 9.13.0 < 9.14.3.9, >= 9.15.0 < 9.15.1.17, >= 9.16.0 < 9.16.2.3, 009.009(002.085), 009.014(002.106)
Fixed versions
9.8.4.40, 6.2.3.17, 6.4.0.13, 6.6.5, 6.7.0.3, 7.0.1, 9.12.4.26, 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-119, CWE-400