description: 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.
problem types: CWE-287: Improper Authentication
affected:
{
product: USG/ZyWALL series firmware
vendor: Zyxel
versions:
status: affected, version: 4.32 through 4.71
}
{
product: USG FLEX series firmware
vendor: Zyxel
versions:
status: affected, version: 4.50 through 5.21
}
{
product: ATP series firmware
vendor: Zyxel
versions:
status: affected, version: 4.32 through 5.21
}
{
product: VPN series firmware
vendor: Zyxel
versions:
status: affected, version: 4.32 through 5.21
}
metrics:
cvssV3_1: [
attackComplexity: LOW
attackVector: NETWORK
availabilityImpact: NONE
baseScore: 6.5
baseSeverity: MEDIUM
confidentialityImpact: NONE
integrityImpact: HIGH
privilegesRequired: LOW
scope: UNCHANGED
userInteraction: NONE
vectorString: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N
version: 3.1
]