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CVE-2023-34139

HIGH

8.8

CVSS Score

Published: July 17, 2023 at 05:36 PM UTC

Updated: June 17, 2026 at 06:02 AM UTC

30 products affected across 1 vendorUsg Flex 100W FirmwareUSG FLEX 200 firmwareUSG FLEX 700 firmware

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Severity

HIGH8.8

Exploit prediction

EPSS 0.8%

SSVC

No known exploit

Description

A command injection vulnerability in the Free Time WiFi hotspot feature of the Zyxel USG FLEX series firmware versions 4.50 through 5.36 Patch 2 and VPN series firmware versions 4.20 through 5.36 Patch 2, could allow an unauthenticated, LAN-based attacker to execute some OS commands on an affected device.

Affected

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

Usg 2200-vpn Firmware · Zyxel

95%

4.20 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-2200-vpn (same device)

Usg Flex 100 Firmware · Zyxel

95%

4.50 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-100 (same device)

Usg Flex 100W Firmware · Zyxel

95%

4.50 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-100w (same device)

USG FLEX 200 firmware · Zyxel

95%

4.50 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-200 (same device)

Usg Flex 50 Firmware · Zyxel

95%

4.50 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-50 (same device)

USG FLEX 500 firmware · Zyxel

95%

4.50 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-500 (same device)

Usg Flex 50W Firmware · Zyxel

95%

4.50 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

USG FLEX 700 firmware · Zyxel

95%

4.50 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-700 (same device)

Zywall VPN 50 Firmware · Zyxel

95%

4.20 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-zywall-vpn-50 (same device) · zyxel-zywall-vpn50 (same device)

Zywall VPN100 Firmware · Zyxel

95%

4.20 ≤ v < 5.37

Affected range stops below 5.37, so it looks safe — our inference, not a vendor statement

zyxel-zywall-vpn-100 (same device) · zyxel-zywall-vpn100 (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

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

References (1)

Vendor Advisory

Source: [email protected]

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

SSVC — Action Prioritization

SSVCNo known exploitNot automatableTotal impact

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

CVSS

8.8HIGHZyxel

Attack Vector: ADJACENT_NETWORK
Complexity: LOW
Privileges: NONE
User Interaction: NONE
Scope: UNCHANGED
Confidentiality: HIGH
Integrity: HIGH
Availability: HIGH

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-78

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