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CVE-2023-27990

MEDIUM

4.8

CVSS Score

Published: April 24, 2023 at 12:00 AM UTC

Updated: June 17, 2026 at 05:46 AM UTC

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

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Severity

MEDIUM4.8

Exploit prediction

EPSS 0.3%

Description

The cross-site scripting (XSS) vulnerability in Zyxel ATP series firmware versions 4.32 through 5.35, USG FLEX series firmware versions 4.50 through 5.35, USG FLEX 50(W) firmware versions 4.16 through 5.35, USG20(W)-VPN firmware versions 4.16 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow an authenticated attacker with administrator privileges to store malicious scripts in a vulnerable device. A successful XSS attack could then result in the stored malicious scripts being executed when the user visits the Logs page of the GUI on the device.

Affected

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

ATP100 Firmware · Zyxel

95%

4.32 ≤ v < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

ATP100W Firmware · Zyxel

95%

4.32 ≤ v < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

zyxel-atp100w (same device)

ATP200 Firmware · Zyxel

95%

4.32 ≤ v < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

zyxel-atp200 (same device)

ATP500 Firmware · Zyxel

95%

4.32 ≤ v < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

zyxel-atp500 (same device)

ATP700 Firmware · Zyxel

95%

4.32 ≤ v < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

zyxel-atp700 (same device)

ATP800 Firmware · Zyxel

95%

4.32 ≤ v < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

zyxel-atp800 (same device)

Usg 20W VPN Firmware · Zyxel

95%

4.16 ≤ v < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

Usg Flex 100 Firmware · Zyxel

95%

4.50 ≤ v < 5.36

Affected range stops below 5.36, 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 < 5.36

Affected range stops below 5.36, 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 < 5.36

Affected range stops below 5.36, so it looks safe — our inference, not a vendor statement

zyxel-usg-flex-200 (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-xss-vulnerability-and-post-authentication-command-injection-vulnerability-in-firewalls

References (1)

Vendor Advisory

Source: [email protected]

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-xss-vulnerability-and-post-authentication-command-injection-vulnerability-in-firewalls

CVSS

4.8MEDIUMZyxel

Attack Vector: NETWORK
Complexity: LOW
Privileges: HIGH
User Interaction: REQUIRED
Scope: CHANGED
Confidentiality: LOW
Integrity: LOW
Availability: NONE

Vector?

Quick Info

StatusMODIFIED

CWE

CWE-79

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