CVE & CISA-KEV Catalog

CVE-2023-27990

MEDIUM
4.8
CVSS v3
NVD

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.

CWE-79Cross-Site Scripting (XSS)

How to fix

Remediation Available
atp100 firmwareNVD
Affected:>= 4.32, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
atp100w firmwareNVD
Affected:>= 4.32, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
atp200 firmwareNVD
Affected:>= 4.32, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
atp500 firmwareNVD
Affected:>= 4.32, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
atp700 firmwareNVD
Affected:>= 4.32, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
atp800 firmwareNVD
Affected:>= 4.32, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg20-vpn firmwareNVD
Affected:>= 4.30, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg 20w-vpn firmwareNVD
Affected:>= 4.16, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg flex 100 firmwareNVD
Affected:>= 4.50, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg flex 100w firmwareNVD
Affected:>= 4.50, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg flex 200 firmwareNVD
Affected:>= 4.50, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg flex 500 firmwareNVD
Affected:>= 4.50, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg flex 50 firmwareNVD
Affected:>= 4.50, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg flex 50w firmwareNVD
Affected:>= 4.16, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
usg flex 700 firmwareNVD
Affected:>= 4.50, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
vpn1000 firmwareNVD
Affected:>= 4.30, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
vpn100 firmwareNVD
Affected:>= 4.30, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
vpn300 firmwareNVD
Affected:>= 4.30, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD
vpn50 firmwareNVD
Affected:>= 4.30, < 5.36Fixed in:5.36CVE-2023-27990derived from NVD

Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.

CVSS v3 Vector

Exploitability

Attack VectorNetwork
Attack ComplexityLow
Privileges RequiredHigh
User InteractionRequired
ScopeChanged

Impact

ConfidentialityLow
IntegrityLow
AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N

Exploit Intelligence

0.34%probability of exploitation in 30 days
26thpercentile

Low risk: more likely to be exploited than 26% of all known CVEs.

References

Vendor Advisory1

Related Vulnerabilities

Other CWE-79 (Cross-Site Scripting (XSS)) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2020-11022Medium6.999%-Fix
CVE-2019-3929Critical9.899%KEVFix
CVE-2020-9496Medium6.199%--
CVE-2023-28341Medium6.199%-Fix
CVE-2018-12998Medium6.198%--
CVE-2025-4123High7.698%-Fix
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CVE-2023-27990 severity badge

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-02-25.