Zyxel fixed four bugs in firewalls and access points

Zyxel fixed four bugs in firewalls and access points

Pierluigi Paganini
February 27, 2024

Taiwanese vendor Zyxel warns of security vulnerabilities in its firewalls and access points, including a remote code execution flaw.

Zyxel fixed four bugs in firewalls and access points

Zyxel fixed four bugs in firewalls and access points

Pierluigi Paganini
February 27, 2024

Taiwanese vendor Zyxel warns of security vulnerabilities in its firewalls and access points, including a remote code execution flaw.

Taiwanese networking vendor Zyxel addressed four vulnerabilities, respectively tracked as CVE-2023-6397CVE-2023-6398CVE-2023-6399, and CVE-2023-6764, in its firewalls and access points.

The flaws can be exploited by threat actors to carry out command injection and denial-of-service attacks and to achieve remote code execution.

Below is the list of the flaws addressed by the company:

  • CVE-2023-6397 – A null pointer dereference vulnerability in some firewall versions could allow a LAN-based attacker to cause denial-of-service (DoS) conditions by downloading a crafted RAR compressed file onto a LAN-side host if the firewall has the “Anti-Malware” feature enabled.
  • CVE-2023-6398 – A post-authentication command injection vulnerability in the file upload binary in some firewall and AP versions could allow an authenticated attacker with administrator privileges to execute some operating system (OS) commands on an affected device via FTP.
  • CVE-2023-6399 – A format string vulnerability in some firewall versions could allow an authenticated IPSec VPN user to cause DoS conditions against the “deviceid” daemon by sending a crafted hostname to an affected device if it has the “Device Insight” feature enabled.
  • CVE-2023-6764 – A format string vulnerability in a function of the IPSec VPN feature in some firewall versions could allow an attacker to achieve unauthorized remote code execution by sending a sequence of specially crafted payloads containing an invalid pointer; however, such an attack would require detailed knowledge of an affected device’s memory layout and configuration.

Below are the lists of impacted devices:

Firewall series Affected version Patch availability
CVE-2023-6397 CVE-2023-6398 CVE-2023-6399 CVE-2023-6764
ATP ZLD V4.32 to V5.37 Patch 1 ZLD V4.32 to V5.37 Patch 1 ZLD V5.10 to V5.37 Patch 1 ZLD V4.32 to V5.37 Patch 1 ZLD V5.37 Patch 2
USG FLEX ZLD V4.50 to V5.37 Patch 1 ZLD V4.50 to V5.37 Patch 1 ZLD V5.10 to V5.37 Patch 1 ZLD V4.50 to V5.37 Patch 1 ZLD V5.37 Patch 2
USG FLEX 50(W)/USG20(W)-VPN Not affected ZLD V4.16 to V5.37 Patch 1 ZLD V5.10 to V5.37 Patch 1 ZLD V4.16 to V5.37 Patch 1 ZLD V5.37 Patch 2
USG FLEX H Not affected uOS V1.10 to V1.10 Patch 1 uOS V1.10 to V1.10 Patch 1 Not affected Hotfix is available*
Standard patch uOS V1.20 in April 2024

Table 2. APs affected by CVE-2023-6398

The Taiwanese vendor acknowledged Lays and atdog from TRAPA Security for reporting these flaws.

Customers are recommended to install the security patches as soon as possible.

Follow me on Twitter: @securityaffairs and Facebook

Pierluigi Paganini

(SecurityAffairs – hacking, cyberattack)



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