Missing Access Control in the "Free Time" component of several Zyxel UAG, USG, and ZyWall devices allows a remote attacker to generate guest accounts by directly accessing the account generator. This can lead to unauthorised network access or Denial of Service.
This vulnerability carries a CRITICAL severity rating with a CVSS v3.1 score of 9.1, 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 integrity (unauthorized modifications), and availability (service disruption) for affected systems. Impacting 28 products from zyxel, from zyxel, from zyxel and 25 others, organizations running these solutions should prioritize assessment and patching.
First disclosed in 2019, this vulnerability was reported during a period defined by widespread IoT adoption challenges, mobile security concerns, and the emergence of advanced persistent threat (APT) techniques. Contemporary mitigation strategies focused on secure development practices and third-party component vetting.
2019-06-27T14:15:10.393
2026-06-17T02:14:54.653
Modified
CVSSv3.0: 9.1 (CRITICAL)
AV:N/AC:L/Au:N/C:N/I:P/A:P
10.0
4.9
| Type | Vendor | Product | Version/Range | Vulnerable? |
|---|---|---|---|---|
| Operating System | zyxel | uag2100_firmware | ≤ 4.18\(aaiz.1\)c0 | Yes |
| Hardware | zyxel | uag2100 | - | No |
| Operating System | zyxel | uag4100_firmware | ≤ 4.18\(aatd.1\)c0 | Yes |
| Hardware | zyxel | uag4100 | - | No |
| Operating System | zyxel | uag5100_firmware | ≤ 4.18\(aapn.1\)c0 | Yes |
| Hardware | zyxel | uag5100 | - | No |
| Operating System | zyxel | usg110_firmware | ≤ 4.33\(aaph.0\)c0 | Yes |
| Hardware | zyxel | usg110 | - | No |
| Operating System | zyxel | usg210_firmware | ≤ 4.33\(aapi.0\)c0 | Yes |
| Hardware | zyxel | usg210 | - | No |
| Operating System | zyxel | usg310_firmware | ≤ 4.33\(aapj.0\)c0 | Yes |
| Hardware | zyxel | usg310 | - | No |
| Operating System | zyxel | usg1100_firmware | ≤ 4.33\(aapk.0\)c0 | Yes |
| Hardware | zyxel | usg1100 | - | No |
| Operating System | zyxel | usg1900_firmware | ≤ 4.33\(aapl.0\)c0 | Yes |
| Hardware | zyxel | usg1900 | - | No |
| Operating System | zyxel | usg2200-vpn_firmware | ≤ 4.33\(abae.0\)c0 | Yes |
| Hardware | zyxel | usg2200-vpn | - | No |
| Operating System | zyxel | zywall_vpn100_firmware | ≤ 10.02\(abfv.0\)c0 | Yes |
| Hardware | zyxel | zywall_vpn100 | - | No |
| Operating System | zyxel | zywall_vpn300_firmware | ≤ 10.02\(abfc.0\)c0 | Yes |
| Hardware | zyxel | zywall_vpn300 | - | No |
| Operating System | zyxel | zywall_110_firmware | ≤ 4.33\(aaaa.0\)c0 | Yes |
| Hardware | zyxel | zywall_110 | - | No |
| Operating System | zyxel | zywall_310_firmware | ≤ 4.33\(aaab.0\)c0 | Yes |
| Hardware | zyxel | zywall_310 | - | No |
| Operating System | zyxel | zywall_1100_firmware | ≤ 4.33\(aaac.0\)c0 | Yes |
| Hardware | zyxel | zywall_1100 | - | 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.