#VU83521 Integer overflow in ZyXEL Communications Corp. products - CVE-2023-4398

Vulnerability identifier: #VU83521

Vulnerability risk: Medium

CVSSv4.0: 6.6 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:U/U:Green]

CVE-ID: CVE-2023-4398

CWE-ID: CWE-190

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
ATP series
Hardware solutions / Routers for home users
USG FLEX series
Client/Desktop applications / Antivirus software/Personal firewalls
VPN series
Client/Desktop applications / Antivirus software/Personal firewalls
USG FLEX 50W
Hardware solutions / Firmware
USG20W-VPN
Hardware solutions / Firmware

Vendor: ZyXEL Communications Corp.

Description

The vulnerability allows a remote attacker to perform a denial of service (DoS) attack.

The vulnerability exists due to integer overflow in the source code of the QuickSec IPSec toolkit used in the VPN feature. A remote attacker can pass specially crafted data to the application, trigger integer overflow and cause a denial of service condition on the target system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

ATP series: 4.32 - 5.37

USG FLEX series: 4.50 - 5.37

USG FLEX 50W: 4.16 - 5.37

USG20W-VPN: 4.16 - 5.37

VPN series: 4.30 - 5.37

---

External links
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-in-firewalls-and-aps

---

Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

No. We are not aware of malware exploiting this vulnerability.