Zyxel security advisory for buffer overflow vulnerability in 4G LTE and 5G NR outdoor routers

Zyxel_May Posts: 129  Ally Member
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edited July 2023 in Security Advisories

CVE: CVE-2023-27989


Zyxel has released patches for some 4G LTE and 5G NR outdoor routers affected by a buffer overflow vulnerability. Users are advised to install them for optimal protection.

What are the vulnerabilities?

A buffer overflow vulnerability in the CGI program of some Zyxel 4G LTE and 5G NR outdoor routers could allow a remote authenticated attacker to cause denial of service (DoS) conditions by sending a crafted HTTP request to a vulnerable device.

What versions are vulnerable—and what should you do?

After a thorough investigation, we’ve identified the vulnerable products that are within their vulnerability support period and released patches to address the vulnerability, as shown in the table below.

Affected model

Affected version

Patch availability


V1.00(ABRA.6)C0 and earlier



V1.00(ABQY.5)C0 and earlier



V1.00(ABUV.7)C0 and earlier


Nebula NR7101

V1.15(ACCC.3)C0 and earlier

Hotfix available by July 12, 2023*

Standard patch V1.16(ACCC.0)C0 in Oct. 2023

*Please reach out to your local Zyxel support team for the file.

Got a question?

Please contact your local service rep or visit Zyxel’s Community for further information or assistance.


Thanks to Chengfeng Ye, Prism Research Group - cse hkust for reporting the issue to us.

Revision history

2023-6-6: Initial release.

2023-7-4: Updated the patch availability of Nebula NR7101