Global infos:

A downgrade from two-factor authentication to one-factor authentication vulnerability in the CGI program of Zyxel USG/ZyWALL series firmware versions 4.32 through 4.71, USG FLEX series firmware versions 4.50 through 5.21, ATP series firmware versions 4.32 through 5.21, and VPN series firmware versions 4.32 through 5.21, that could allow an authenticated attacker to bypass the second authentication phase to connect the IPsec VPN server even though the two-factor authentication (2FA) was enabled.

CVE Status: Modified

References:

[email protected]

af854a3a-2127-422b-91ae-364da2661108

Metrics:

Attribute	Value
Attack Complexity	LOW
Attack Vector	NETWORK
Availability Impact	NONE
Base Score	6.5
Base Severity	MEDIUM
Confidentiality Impact	NONE
Integrity Impact	HIGH
Privileges Required	LOW
Scope	UNCHANGED
User Interaction	NONE
Vector String	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
Exploitability Score	2.8
Impact Score	3.6
Source	[email protected]
Type	Secondary

Links:

Exploit-db
Github