CVE-2023-20123: Cisco Duo Authentication for macOS and Duo Authentication for Windows Logon Offline Credentials Replay Vulnerability

Severity: medium (CVSS 4.6 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2023-04-05 · updated 2026-06-17
Weakness: CWE-294

Description

A vulnerability in the offline access mode of Cisco Duo Two-Factor Authentication for macOS and Duo Authentication for Windows Logon and RDP could allow an unauthenticated, physical attacker to replay valid user session credentials and gain unauthorized access to an affected macOS or Windows device. This vulnerability exists because session credentials do not properly expire. An attacker could exploit this vulnerability by replaying previously used multifactor authentication (MFA) codes to bypass MFA protection. A successful exploit could allow the attacker to gain unauthorized access to the affected device.

Affected products

Cisco Duo: before 2.0.1 — fixed in 2.0.1
Cisco Duo Authentication for Windows Logon and RDP: before 4.2.2 — fixed in 4.2.2

How to fix

Upgrade to a fixed version: Cisco Duo 2.0.1; Cisco Duo Authentication for Windows Logon and RDP 4.2.2. Check the vendor advisory for mitigations.

References

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