What’s Vulnerable › Vulnerabilities

CVE-2023-22915

• Severity: high (CVSS 7.5 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 1.1% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2023-04-24 · updated 2026-06-17
• Weakness: CWE-120

Description

A buffer overflow vulnerability in the “fbwifi_forward.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.30 through 5.35, USG20(W)-VPN firmware versions 4.30 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote unauthenticated attacker to cause DoS conditions by sending a crafted HTTP request if the Facebook WiFi function were enabled on an affected device.

Affected products

• Zyxel USG 20(W)-VPN firmware: from 4.30 through 5.35
• Zyxel firewall (ZLD): from 4.50 through 5.35
• Zyxel USG FLEX 100(W) firmware: from 4.50 through 5.35
• Zyxel USG FLEX 200 firmware: from 4.50 through 5.35
• Zyxel USG FLEX 500 firmware: from 4.50 through 5.35
• Zyxel Usg Flex 50 Firmware: from 4.50 through 5.35
• Zyxel USG FLEX 50(W) firmware: from 4.30 through 5.35
• Zyxel USG FLEX 700 firmware: from 4.50 through 5.35
• Zyxel Vpn1000 Firmware: from 4.50 through 5.35
• Zyxel Vpn100 Firmware: from 4.50 through 5.35
• Zyxel Vpn300 Firmware: from 4.50 through 5.35
• Zyxel Vpn50 Firmware: from 4.50 through 5.35

References

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

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