Zyxel has released patches to address 15 security issues impacting network-attached storage (NAS), firewall, and access point (AP) devices, including three critical flaws that could lead to authentication bypass and command injection.

The three vulnerabilities are listed below -

• CVE-2023-35138 (CVSS score: 9.8) - A command injection vulnerability that could allow an unauthenticated attacker to execute some operating system commands by sending a crafted HTTP POST request.
• CVE-2023-4473 (CVSS score: 9.8) - A command injection vulnerability in the web server that could allow an unauthenticated attacker to execute some operating system commands by sending a crafted URL to a vulnerable device.
• CVE-2023-4474 (CVSS score: 9.8) - An improper neutralization of special elements vulnerability that could allow an unauthenticated attacker to execute some operating system commands by sending a crafted URL to a vulnerable device.

Also patched by Zyxel are three high-severity flaws (CVE-2023-35137, CVE-2023-37927, and CVE-2023-37928) that, if successfully exploited, could allow attackers to obtain system information and execute arbitrary commands. It's worth noting that both CVE-2023-37927 and CVE-2023-37928 require authentication.

The flaws impact the following models and versions -

• NAS326 - versions V5.21(AAZF.14)C0 and earlier (Patched in V5.21(AAZF.15)C0)
• NAS542 - versions V5.21(ABAG.11)C0 and earlier (Patched in V5.21(ABAG.12)C0)

The advisory comes days after the Taiwanese networking vendor shipped fixes for nine flaws in select firewall and access point (AP) versions, some of which could be weaponized to access system files and administrator logs, as well as cause a denial-of-service (DoS) condition.

With Zyxel devices often exploited by threat actors, it's highly recommended that users apply the latest updates to mitigate potential threats.