Zyxel security advisory for multiple buffer overflow vulnerabilities of firewalls

Zyxel_May

CVEs: CVE-2023-33009, CVE-2023-33010

Summary

Zyxel has released patches for firewalls affected by multiple buffer overflow vulnerabilities. Users are advised to install them for optimal protection.

What are the vulnerabilities?

CVE-2023-33009

A buffer overflow vulnerability in the notification function in some firewall versions could allow an unauthenticated attacker to cause denial-of-service (DoS) conditions and even a remote code execution on an affected device.

CVE-2023-33010

A buffer overflow vulnerability in the ID processing function in some firewall versions could allow an unauthenticated attacker to cause DoS conditions and even a remote code execution on an affected device.

What versions are vulnerable—and what should you do?

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

Affected series	Affected version for CVE-2023-33009	Affected version for CVE-2023-33010	Patch availability
ATP	ZLD V4.60 to V5.36 Patch 1	ZLD V4.32 to V5.36 Patch 1	ZLD V5.36 Patch 2
USG FLEX	ZLD V4.60 to V5.36 Patch 1	ZLD V4.50 to V5.36 Patch 1	ZLD V5.36 Patch 2
USG FLEX50(W) / USG20(W)-VPN	ZLD V4.60 to V5.36 Patch 1	ZLD V4.25 to V5.36 Patch 1	ZLD V5.36 Patch 2
VPN	ZLD V4.60 to V5.36 Patch 1	ZLD V4.30 to V5.36 Patch 1	ZLD V5.36 Patch 2
ZyWALL/USG	ZLD V4.60 to V4.73 Patch 1	ZLD V4.25 to V4.73 Patch 1	ZLD V4.73 Patch 2

Got a question?

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

Acknowledgment

Thanks to the following security consultancies:

• Lays and atdog from TRAPA Security, followed by
• STAR Labs SG

Revision history

2023-5-24: Initial release

2023-6-15: Modified the affected firmware versions