A buffer overflow vulnerability in the notification function in Zyxel ATP series firmware versions 4.60 through 5.36 Patch 1, USG FLEX series firmware versions 4.60 through 5.36 Patch 1, USG FLEX 50(W) firmware versions 4.60 through 5.36 Patch 1, USG20(W)-VPN firmware versions 4.60 through 5.36 Patch 1, VPN series firmware versions 4.60 through 5.36 Patch 1, ZyWALL/USG series firmware versions 4.60 through 4.73 Patch 1, could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.
This vulnerability carries a CRITICAL severity rating with a CVSS v3.1 score of 9.8, indicating it can be exploited remotely over the network with relatively low complexity without requiring user interaction and does not require pre-existing privileges . The vulnerability impacts confidentiality (data exposure), integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 46 products from zyxel, from zyxel, from zyxel and 43 others, organizations running these solutions should prioritize assessment and patching.
Reported in 2023, this vulnerability emerged during an era marked by increased sophistication in supply chain attacks, cloud infrastructure vulnerabilities, and software-as-a-service (SaaS) security challenges. Security practices during this period emphasized zero-trust architectures, container security, and API protection.
2023-05-24T13:15:09.560
2026-02-26T15:03:56.120
Analyzed
CVSSv3.1: 9.8 (CRITICAL)
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Operating System | zyxel | atp100_firmware | < 5.36 | Yes |
| Operating System | zyxel | atp100_firmware | 5.36 | Yes |
| Operating System | zyxel | atp100_firmware | 5.36 | Yes |
| Hardware | zyxel | atp100 | - | No |
| Operating System | zyxel | atp200_firmware | < 5.36 | Yes |
| Operating System | zyxel | atp200_firmware | 5.36 | Yes |
| Operating System | zyxel | atp200_firmware | 5.36 | Yes |
| Hardware | zyxel | atp200 | - | No |
| Operating System | zyxel | atp500_firmware | < 5.36 | Yes |
| Operating System | zyxel | atp500_firmware | 5.36 | Yes |
| Operating System | zyxel | atp500_firmware | 5.36 | Yes |
| Hardware | zyxel | atp500 | - | No |
| Operating System | zyxel | atp100w_firmware | < 5.36 | Yes |
| Operating System | zyxel | atp100w_firmware | 5.36 | Yes |
| Operating System | zyxel | atp100w_firmware | 5.36 | Yes |
| Hardware | zyxel | atp100w | - | No |
| Operating System | zyxel | atp700_firmware | < 5.36 | Yes |
| Operating System | zyxel | atp700_firmware | 5.36 | Yes |
| Operating System | zyxel | atp700_firmware | 5.36 | Yes |
| Hardware | zyxel | atp700 | - | No |
| Operating System | zyxel | atp800_firmware | < 5.36 | Yes |
| Operating System | zyxel | atp800_firmware | 5.36 | Yes |
| Operating System | zyxel | atp800_firmware | 5.36 | Yes |
| Hardware | zyxel | atp800 | - | No |
| Operating System | zyxel | usg_flex_100_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_flex_100_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_flex_100_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_flex_100 | - | No |
| Operating System | zyxel | usg_flex_50_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_flex_50_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_flex_50_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_flex_50 | - | No |
| Operating System | zyxel | usg_flex_200_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_flex_200_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_flex_200_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_flex_200 | - | No |
| Operating System | zyxel | usg_flex_500_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_flex_500_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_flex_500_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_flex_500 | - | No |
| Operating System | zyxel | usg_flex_700_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_flex_700_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_flex_700_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_flex_700 | - | No |
| Operating System | zyxel | usg_flex_100w_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_flex_100w_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_flex_100w_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_flex_100w | - | No |
| Operating System | zyxel | usg_flex_50w_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_flex_50w_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_flex_50w_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_flex_50w | - | No |
| Operating System | zyxel | usg_20w-vpn_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg_20w-vpn_firmware | 5.36 | Yes |
| Operating System | zyxel | usg_20w-vpn_firmware | 5.36 | Yes |
| Hardware | zyxel | usg_20w-vpn | - | No |
| Operating System | zyxel | vpn100_firmware | < 5.36 | Yes |
| Operating System | zyxel | vpn100_firmware | 5.36 | Yes |
| Operating System | zyxel | vpn100_firmware | 5.36 | Yes |
| Hardware | zyxel | vpn100 | - | No |
| Operating System | zyxel | vpn50_firmware | < 5.36 | Yes |
| Operating System | zyxel | vpn50_firmware | 5.36 | Yes |
| Operating System | zyxel | vpn50_firmware | 5.36 | Yes |
| Hardware | zyxel | vpn50 | - | No |
| Operating System | zyxel | vpn300_firmware | < 5.36 | Yes |
| Operating System | zyxel | vpn300_firmware | 5.36 | Yes |
| Operating System | zyxel | vpn300_firmware | 5.36 | Yes |
| Hardware | zyxel | vpn300 | - | No |
| Operating System | zyxel | vpn1000_firmware | < 5.36 | Yes |
| Operating System | zyxel | vpn1000_firmware | 5.36 | Yes |
| Operating System | zyxel | vpn1000_firmware | 5.36 | Yes |
| Hardware | zyxel | vpn1000 | - | No |
| Operating System | zyxel | usg20-vpn_firmware | < 5.36 | Yes |
| Operating System | zyxel | usg20-vpn_firmware | 5.36 | Yes |
| Operating System | zyxel | usg20-vpn_firmware | 5.36 | Yes |
| Hardware | zyxel | usg20-vpn | - | No |
| Operating System | zyxel | usg_40_firmware | < 4.73 | Yes |
| Operating System | zyxel | usg_40_firmware | 4.73 | Yes |
| Operating System | zyxel | usg_40_firmware | 4.73 | Yes |
| Hardware | zyxel | usg_40 | - | No |
| Operating System | zyxel | usg_40w_firmware | < 4.73 | Yes |
| Operating System | zyxel | usg_40w_firmware | 4.73 | Yes |
| Operating System | zyxel | usg_40w_firmware | 4.73 | Yes |
| Hardware | zyxel | usg_40w | - | No |
| Operating System | zyxel | usg_60w_firmware | < 4.73 | Yes |
| Operating System | zyxel | usg_60w_firmware | 4.73 | Yes |
| Operating System | zyxel | usg_60w_firmware | 4.73 | Yes |
| Hardware | zyxel | usg_60w | - | No |
| Operating System | zyxel | usg_60_firmware | < 4.73 | Yes |
| Operating System | zyxel | usg_60_firmware | 4.73 | Yes |
| Operating System | zyxel | usg_60_firmware | 4.73 | Yes |
| Hardware | zyxel | usg_60 | - | No |
SecUtils normalizes and enriches National Vulnerability Database (NVD) records by standardizing vendor and product identifiers, aggregating vulnerability metadata from both NVD and MITRE sources, and providing structured context for security teams. For zyxel's affected products, we extract Common Platform Enumeration (CPE) data, Common Weakness Enumeration (CWE) classifications, CVSS severity metrics, and reference data to enable rapid vulnerability prioritization and asset correlation. This record contains no exploit code, proof-of-concept instructions, or attack methodologies—only defensive intelligence necessary for patch management, risk assessment, and security operations.