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CVE-2023-22915

HIGH
7.5
CVSS Score
Published: April 24, 2023 at 12:00 AM UTC
Updated: June 17, 2026 at 05:36 AM UTC
28 products affected across 1 vendorUsg Flex 100W FirmwareUSG FLEX 200 firmwareUSG FLEX 700 firmware

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Severity
HIGH7.5
Exploit prediction
EPSS 1%
SSVC
No known exploit

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Usg 20W VPN Firmware· Zyxel
95%
4.30 ≤ v ≤ 5.35
Usg Flex 100 Firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-usg-flex-100 (same device)
Usg Flex 100W Firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-usg-flex-100w (same device)
USG FLEX 200 firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-usg-flex-200 (same device)
Usg Flex 50 Firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-usg-flex-50 (same device)
USG FLEX 500 firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-usg-flex-500 (same device)
Usg Flex 50W Firmware· Zyxel
95%
4.30 ≤ v ≤ 5.35
USG FLEX 700 firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-usg-flex-700 (same device)
VPN100 Firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-vpn100 (same device)
VPN1000 Firmware· Zyxel
95%
4.50 ≤ v ≤ 5.35
zyxel-vpn1000 (same device)

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (1)

Vendor Advisory
Source: [email protected]
https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-of-firewalls-and-aps

SSVC — Action Prioritization

SSVCNo known exploitAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

7.5HIGHZyxel
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
NONE
Integrity
NONE
Availability
HIGH
Vector?

Quick Info

StatusMODIFIED
CWE
CWE-120

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