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Secure Firewall Threat DefenseApplication · Cisco

CVE-2023-20006

HIGH · 7.5 CVSS v3.1 Published 2023-06-28
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
84/100
Remediation priority · High
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
A vulnerability in the hardware-based SSL/TLS cryptography functionality of Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco Firepower 2100 Series Appliances could allow an unauthenticated, remote attacker to cause an affected device to reload unexpectedly, resulting in a denial of service (DoS) condition. This vulnerability is due to an implementation error within the cryptographic functions for SSL/TLS traffic processing when they are offloaded to the hardware. An attacker could exploit this vulnerability by sending a crafted stream of SSL/TLS traffic to an affected device. A successful exploit could allow the attacker to cause an unexpected error in the hardware-based cryptography engine, which could cause the device to reload.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

This is a vulnerability in the hardware-based SSL/TLS cryptography offloading feature of Cisco ASA and FTD software running on Firepower 2100 Series appliances. The flaw exists in how cryptographic functions process SSL/TLS traffic when it is offloaded to the hardware, where an implementation error causes the hardware cryptography engine to error out when receiving specially crafted SSL/TLS packets, triggering an unexpected device reload.

MitigationApply the Cisco patch for CVE-2023-20006 to affected ASA and FTD software versions. As a workaround, if SSL/TLS hardware offloading can be disabled without unacceptable performance impact, that may reduce the attack surface until the patch is applied.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Secure Firewall Threat DefenseApplication
Affected:= 7.2.1= 7.2.2= 7.2.3
Adaptive Security Appliance SoftwareOperating system
Affected:= 9.16.4= 9.18.2= 9.18.2.5

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the hardware platform
    Run 'show platform' or check the device model to confirm it is a Firepower 2100 Series appliance
    Affected if The device is NOT a Firepower 2100 Series appliance (vulnerability only affects this specific hardware platform)
  2. Check the ASA software version
    Run 'show version' on Cisco ASA to obtain the running software version
    Affected if The ASA version is 9.16.4, 9.18.2, or 9.18.2.5
  3. Check the FTD software version
    Run 'show version' on Cisco FTD to obtain the running software version
    Affected if The FTD version is 7.2.1, 7.2.2, or 7.2.3
  4. Verify SSL/TLS hardware offloading is enabled
    Run 'show crypto hardware accelerator' or 'show crypto ssl offload' to check if SSL/TLS hardware offloading is active
    Affected if SSL/TLS hardware offloading is enabled - this is required for the vulnerability to be triggered

A device is affected if it is a Firepower 2100 Series appliance running the listed ASA or FTD versions AND has SSL/TLS hardware offloading enabled, as the flaw is triggered when the hardware cryptography engine processes specially crafted SSL/TLS packets.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Apply the Cisco patch for CVE-2023-20006 to affected ASA and FTD software versions. As a workaround, if SSL/TLS hardware offloading can be disabled without unacceptable performance impact, that may reduce the attack surface until the patch is applied.

Fix this in Secure Firewall Threat Defense Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA1.0 h
10.0 hours of engineering $1,750
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-20006 in production — separate from our analysis above.

No notes yet

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
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