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Adaptive Security ApplianceApplication · Cisco

CVE-2023-20107

HIGH · 7.5 CVSS v3.1 Published 2023-03-23
Fix available
A fix is available. Upgrade to 6.4.0 / 9.12.1 or later.
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 deterministic random bit generator (DRBG), also known as pseudorandom number generator (PRNG), in Cisco Adaptive Security Appliance (ASA) Software and Cisco Firepower Threat Defense (FTD) Software for Cisco ASA 5506-X, ASA 5508-X, and ASA 5516-X Firewalls could allow an unauthenticated, remote attacker to cause a cryptographic collision, enabling the attacker to discover the private key of an affected device. This vulnerability is due to insufficient entropy in the DRBG for the affected hardware platforms when generating cryptographic keys. An attacker could exploit this vulnerability by generating a large number of cryptographic keys on an affected device and looking for collisions with target devices. A successful exploit could allow the attacker to impersonate an affected target device or to decrypt traffic secured by an affected key that is sent to or from an affected target device.

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 · moderate confidence

A vulnerability in the deterministic random bit generator (DRBG) of Cisco ASA and FTD software for specific firewall models (5506-X, 5508-X, 5516-X) allows discovery of private keys due to insufficient entropy in the PRNG, enabling cryptographic collisions that permit device impersonation and traffic decryption.

MitigationApply Cisco security updates for ASA/FTD software to address the entropy weakness; if patches are unavailable, consider network segmentation and monitoring for signs of impersonation attacks.

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
Adaptive Security ApplianceApplication
Affected:< 9.12.1
Secure Firewall Threat DefenseApplication
Affected:< 6.4.0

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
High
Integrity
None
Availability
None

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

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 firewall model
    Run 'show version' or 'show inventory' on the device CLI to confirm the exact model number
    Affected if The model is NOT one of: 5506-X, 5508-X, or 5516-X (these are the only affected models)
  2. Check Cisco ASA software version
    Run 'show version' and locate the 'ASA' or 'Adaptive Security Appliance' software version line
    Affected if The ASA version is 9.12.1 or higher (versions below 9.12.1 are affected)
  3. Check Cisco FTD software version
    Run 'show version' and locate the 'Firepower Threat Defense' or 'FTD' software version line
    Affected if The FTD version is 6.4.0 or higher (versions below 6.4.0 are affected)
  4. Confirm the device performs cryptographic operations
    Verify the device is actively using VPN, SSL inspection, or certificate-based authentication by reviewing 'show run' or current configuration
    Affected if The device uses any cryptographic functions (VPN, SSL decryption, certificates) - this is required for the vulnerability to be exploitable in practice

You are affected if your device is a 5506-X, 5508-X, or 5516-X model running ASA version below 9.12.1 or FTD version below 6.4.0, and the device is performing cryptographic operations such as VPN or SSL inspection.

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.

dbcve · scoped
Upgrade available Upgrade to 6.4.0 / 9.12.1 or later
Fixed in 6.4.09.12.1
Interim mitigation

Apply Cisco security updates for ASA/FTD software to address the entropy weakness; if patches are unavailable, consider network segmentation and monitoring for signs of impersonation attacks.

Recommended fix High confidence

Cisco ASA 9.12.1 or later; Cisco FTD 6.4.0 or later

  1. Identify the current version of Cisco ASA Software or FTD Software running on the affected devices (ASA 5506-X, ASA 5508-X, ASA 5516-X).
  2. For Cisco ASA Software: Upgrade to version 9.12.1 or later.
  3. For Cisco Firepower Threat Defense Software: Upgrade to version 6.4.0 or later.
  4. Verify the upgrade was successful by confirming the new software version is installed.
  5. After upgrade, regenerate any cryptographic keys that were generated while running the vulnerable software version to ensure new keys use proper entropy.
  6. Consult Cisco ASA and FTD upgrade guides for any required migration steps or compatibility checks before upgrading.
Caveat Review Cisco upgrade documentation for any migration steps or compatibility considerations specific to your device configuration.

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Adaptive Security Appliance Scoped from the published advisory
  • Consultation12.0 h
  • Implementation20.0 h
  • Testing10.0 h
  • Review / QA6.0 h
48.0 hours of engineering $8,580
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Scan for this in your stack

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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-2023-20107 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
  • No spam, self-promotion, credentials, or personal data