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DuoApplication · Cisco

CVE-2023-20199

MEDIUM · 6.6 CVSS v3.1 Published 2023-06-28
Fix available
A fix is available. Upgrade to 2.0.2 or later.
See remediation →
68/100
Remediation priority · Elevated
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 Cisco Duo Two-Factor Authentication for macOS could allow an authenticated, physical attacker to bypass secondary authentication and access an affected macOS device. This vulnerability is due to the incorrect handling of responses from Cisco Duo when the application is configured to fail open. An attacker with primary user credentials could exploit this vulnerability by attempting to authenticate to an affected device. A successful exploit could allow the attacker to access the affected device without valid permission.

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

Cisco Duo Two-Factor Authentication for macOS contains a vulnerability where incorrect handling of authentication responses when configured to 'fail open' allows an authenticated attacker with primary user credentials to bypass secondary 2FA and gain access to the affected macOS device without valid permission.

MitigationConfigure Cisco Duo to fail closed rather than fail open, or update to the latest version if a patch is available, to ensure authentication attempts are properly denied when Duo cannot validate the secondary factor.

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
DuoApplication
Affected:>= 2.0.0, < 2.0.2

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
Physical
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:P/AC:L/PR:L/UI:N/S:U/C:H/I:H/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. Check Cisco Duo version installed on macOS
    Open Terminal and run: ls /Applications | grep -i duo to locate the app, then check the version using: defaults read /Applications/Duo\ Security.app/Contents/Info.plist CFBundleShortVersionString or system_profiler SPApplicationsDataType | grep -A5 Duo
    Affected if The version shown is 2.0.0, 2.0.1, or 2.0.2 (any version >=2.0.0 and <2.0.2)
  2. Verify Duo authentication policy configuration
    Open Cisco Duo Admin Panel and navigate to the macOS endpoint policy settings, or check the local Duo configuration file at ~/Library/Preferences/com.duosecurity.duo.plist for the 'fail_open' or 'failopen' setting
    Affected if The policy is set to allow 'fail open' behavior, meaning authentication attempts succeed when Duo cannot reach the verification server
  3. Confirm primary credential availability to potential attacker
    Review system access logs or directory service (such as Active Directory or local accounts) to determine if an attacker already has valid primary (first-factor) credentials for the macOS user account
    Affected if Valid primary user credentials exist that could be combined with the fail-open configuration to bypass the secondary factor

You are affected if Cisco Duo for macOS version 2.0.0 through 2.0.2 is installed AND the fail-open authentication policy is enabled, allowing an attacker with primary credentials to bypass 2FA.

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 2.0.2 or later
Fixed in 2.0.2
Interim mitigation

Configure Cisco Duo to fail closed rather than fail open, or update to the latest version if a patch is available, to ensure authentication attempts are properly denied when Duo cannot validate the secondary factor.

Recommended fix High confidence

Cisco Duo Two-Factor Authentication for macOS version 2.0.2 or later

  1. Verify the current installed version of Cisco Duo Two-Factor Authentication for macOS by checking the application in /Applications or via system preferences
  2. Navigate to the official Cisco Duo downloads page or your organization's Duo admin console to obtain the latest version
  3. Download Cisco Duo for macOS version 2.0.2 or later
  4. Quit the running Duo Authentication app if currently active
  5. Install the new version by running the downloaded installer package
  6. Restart the Duo Authentication service or reboot the macOS device to ensure the update takes effect
  7. Verify the installed version is now 2.0.2 or higher

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

Fix this in Duo Scoped from the published advisory
  • Consultation3.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,440
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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-2023-20199 in production — separate from our analysis above.

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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