Home/CVE/A buffer overflow vulnerability in the “fbwifi_forward.cgi” CGI program of Zyxel USG FLEX series firmware versions 4
CVE

CVE-2023-22915

A buffer overflow vulnerability in the “fbwifi_forward.cgi” CGI program of Zyxel USG FLEX series firmware versions 4

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.

HIGH · CVSS 7.5 EPSS 0.01071
Schedule remediation
  • SSVC automatable: yes - attacks can be scripted at scale
  • CVSS base score ≥ 7.0
Sigma rules0 YARA rules0
⬡

Weakness Classification

CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
CWE-120Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
▤

Affected Products & Versions

12
zyxel usg flex 100 firmware>= 4.50 and <= 5.35
zyxel usg flex 100w firmware>= 4.50 and <= 5.35
zyxel usg flex 200 firmware>= 4.50 and <= 5.35
zyxel usg flex 50 firmware>= 4.50 and <= 5.35
zyxel usg flex 50w firmware>= 4.30 and <= 5.35
zyxel usg flex 500 firmware>= 4.50 and <= 5.35
zyxel usg flex 700 firmware>= 4.50 and <= 5.35
zyxel vpn100 firmware>= 4.50 and <= 5.35
▣

Scoring & Timeline

7.5
HIGH · CVSS v3.1 · security@zyxel.com.tw
View on NVD
Attack Vector
Network Adjacent Local Physical
Attack Complexity
Low High
Privileges Required
None Low High
User Interaction
None Required
Scope
Unchanged Changed
Confidentiality
None Low High
Integrity
None Low High
Availability
None Low High
Published to NVD24 Apr 2023 · 05:15 PM
CVSS VectorCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
SSVC triage · cisa-vulnrichment
Exploitation
none
Automatable
yes
Technical impact
partial
SSVC asks the questions that actually drive patch urgency: is it being exploited, can attacks be automated, and how total is the impact.
🔗

References & Sources

1
Source URLs (vendor pages, mailing lists, write-ups). Exploit/PoC links are in their own section above to avoid duplication.
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-of-firewalls-and-apsVendor Advisory
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