CVE-2021-35029
CRITICALCVSS 9.8/10EPSS 2.25%
Last modified
CVE-2021-35029 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. EPSS estimates a 2.25% chance of exploitation in the next 30 days.
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.
Metrics
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness Enumeration
Affected Software
| Vendor | Product | Versions |
|---|---|---|
| Zyxel | Usg1900 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg1100 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg310 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg210 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg110 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg40 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg40w Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg60 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg60w Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg300 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg1000 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg2000 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg20 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg20w Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg50 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg100 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg200 Firmware | >= 4.35, <= 4.64 |
| Zyxel | Usg Flex 100 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Usg Flex 200 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Usg Flex 500 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Usg Flex 100w Firmware | >= 4.35, <= 5.01 |
| Zyxel | Usg Flex 700 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Atp100 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Atp100w Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Atp200 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Atp500 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Atp700 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Atp800 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Vpn50 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Vpn100 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall Vpn300 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Usg20-Vpn Firmware | >= 4.35, <= 5.01 |
| Zyxel | Usg20w-Vpn Firmware | >= 4.35, <= 5.01 |
| Zyxel | Usg2200-Vpn Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall 110 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall 310 Firmware | >= 4.35, <= 5.01 |
| Zyxel | Zywall 1100 Firmware | >= 4.35, <= 5.01 |
References
Timeline
- Published
- Last Modified
- Status
- Modified
Frequently Asked Questions
What is CVE-2021-35029?
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.
How severe is CVE-2021-35029?
CVE-2021-35029 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 2.25% probability of exploitation in the next 30 days.
How do I fix CVE-2021-35029?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.
How Strix Helps
- How Strix found a critical auth bypass in etcdStrix autonomously discovered a critical authentication bypass in etcd, later designated CVE-2026-33413.
- Autonomous PentestingAI agents that find and validate exploitable vulnerabilities like this one across your applications.
- PR ReviewsPentest every pull request so vulnerable code is caught before it ships to production.
- AI Penetration TestingHow AI-driven penetration testing continuously covers your attack surface.
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Are you affected by CVE-2021-35029?
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Scan your code nowSource: NVD / NIST