CVE-2023-20199

Physical MFA bypass via mishandled service responses

Published Jun 28, 2023 · Updated Aug 2, 2024

Authentication bypass in Cisco Duo Two-Factor Authentication for macOS 2.0.0 through 2.0.1 allows physically proximate attackers to skip MFA. When fail open is enabled, the macOS login plugin incorrectly treats certain Duo service responses as authorization to continue after primary authentication. Physical access and valid primary credentials are required; successful exploitation opens the local macOS session without secondary authentication.

CVSS severity6.2
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Authentication bypass in Cisco Duo Two-Factor Authentication for macOS 2.0.0 through 2.0.1 allows physically proximate attackers to skip MFA. When fail open is enabled, the macOS login plugin incorrectly treats certain Duo service responses as authorization to continue after primary authentication. Physical access and valid primary credentials are required; successful exploitation opens the local macOS session without secondary authentication.

The record

CVE
CVE-2023-20199
Published
Jun 28, 2023
Updated
Aug 2, 2024
Vendor
ClamAV
Product
Cisco Duo
Classifications
CWE-287, T1078
Attack vector
physical
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 28, 2023CVE publishedPublication date reported by the CVE source.
  2. Aug 2, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=n/a

What conditions does exploitation require?

Attack vectorphysical
Required privilegesauthenticated

What is affected?

ClamAV · Cisco Duoversion=n/a

Published CVSS scores

6.6NIST National Vulnerability DatabaseCVSS:3.1/AV:P/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
6.2Cisco Systems, Inc.CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectorphysical
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-287Improper Authentication
T1078Valid Accounts

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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