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ReviewHigh

CVE-2023-20042

Cisco Cisco Adaptive Security Appliance (ASA) Software, Cisco Firepower Threat Defense Software, secure firewall threat defense

A vulnerability in the AnyConnect SSL VPN feature of 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 is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks....

CVSS
8.6
EPSS
0.68%
49.8% percentile
CISA KEV
Not listed
Published
2023.11.02
PRIORITY ASSESSMENT

Review

The CVSS severity warrants an early asset and exposure review.

Known exploitationNot established by KEV
Exploit probability0.68%
Technical severityCVSS 8.6

Vulnerability overview

A vulnerability in the AnyConnect SSL VPN feature of 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 is due to an implementation error within the SSL/TLS session handling process that can prevent the release of a session handler under specific conditions. An attacker could exploit this vulnerability by sending crafted SSL/TLS traffic to an affected device, increasing the probability of session handler leaks....

Affected product and versions

Product
Cisco Cisco Adaptive Security Appliance (ASA) Software, Cisco Firepower Threat Defense Software, secure firewall threat defense
Affected versions
>= 9.16.1, >= 9.16.1.28, >= 9.16.2, >= 9.16.2.3, >= 9.16.2.7, >= 9.16.2.11, >= 9.16.2.13, >= 9.16.2.14, >= 9.16.3, >= 9.16.3.3, >= 9.16.3.14, >= 9.16.3.15, >= 9.16.3.19, >= 9.16.3.23, >= 9.16.4, >= 9.16.4.9, >= 9.17.1, >= 9.17.1.7, >= 9.17.1.9, >= 9.17.1.10
Fixed versions
No verified fixed-version field is available yet

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, Cisco Firepower Threat Defense Software, 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:C/C:N/I:N/A:H
CWE
CWE-404