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CVE-2021-35029

CRITICAL
9.8
CVSS Score
Published: July 2, 2021 at 10:29 AM UTC
Updated: June 17, 2026 at 03:56 AM UTC
79 products affected across 1 vendorUsg Flex 100W FirmwareUSG FLEX 200 firmwareUSG FLEX 700 firmware

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Severity
CRITICAL9.8
Exploit prediction
EPSS 2%

Description

An authentication bypasss vulnerability in the web-based management interface of Zyxel USG/Zywall series firmware versions 4.35 through 4.64 and USG Flex, ATP, and VPN series firmware versions 4.35 through 5.01, which could allow a remote attacker to execute arbitrary commands on an affected device.

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Usg 20W Firmware· Zyxel
95%
4.35 ≤ v ≤ 4.64
zyxel-usg20w (same device)
Usg 20W VPN Firmware· Zyxel
95%
4.35 ≤ v ≤ 5.01
Usg 2200-vpn Firmware· Zyxel
95%
4.35 ≤ v ≤ 5.01
zyxel-usg2200-vpn (same device)
Usg Flex 100 Firmware· Zyxel
95%
4.35 ≤ v ≤ 5.01
zyxel-usg-flex-100 (same device)
Usg Flex 100W Firmware· Zyxel
95%
4.35 ≤ v ≤ 5.01
zyxel-usg-flex-100w (same device)
USG FLEX 200 firmware· Zyxel
95%
4.35 ≤ v ≤ 5.01
zyxel-usg-flex-200 (same device)
USG FLEX 500 firmware· Zyxel
95%
4.35 ≤ v ≤ 5.01
zyxel-usg-flex-500 (same device)
USG FLEX 700 firmware· Zyxel
95%
4.35 ≤ v ≤ 5.01
zyxel-usg-flex-700 (same device)
USG100 Firmware· Zyxel
95%
4.35 ≤ v ≤ 4.64
zyxel-usg100 (same device)
USG1000 Firmware· Zyxel
95%
4.35 ≤ v ≤ 4.64
zyxel-usg1000 (same device)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

x_refsource_MISCVendor Advisory
Source: [email protected]
https://www.zyxel.com/support/Zyxel_security_advisory_for_attacks_against_security_appliances.shtml

CVSS

9.8CRITICALZyxel
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-287

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