CVE & CISA-KEV Catalog

CVE-2023-28771

CRITICALCISA KEVEPSS 100th pctl
9.8
CVSS v3
NVD

Description

Improper error message handling in Zyxel ZyWALL/USG series firmware versions 4.60 through 4.73, VPN series firmware versions 4.60 through 5.35, USG FLEX series firmware versions 4.60 through 5.35, and ATP series firmware versions 4.60 through 5.35, which could allow an unauthenticated attacker to execute some OS commands remotely by sending crafted packets to an affected device.

CWE-78OS Command Injection

How to fix

Remediation Available
atp100 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
atp100w firmwareNVD
Affected:>= 4.60, < 5.35Fixed in:5.35CVE-2023-28771derived from NVD
atp200 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
atp500 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
atp700 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
atp800 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
usg flex 100 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
usg flex 100w firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
usg flex 200 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
usg flex 500 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
usg flex 50 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
usg flex 50w firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
usg flex 700 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
vpn1000 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
vpn100 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
vpn300 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
vpn50 firmwareNVD
Affected:>= 4.60, < 5.36Fixed in:5.36CVE-2023-28771derived from NVD
zywall usg 100 firmwareNVD
Affected:>= 4.60, < 4.73Fixed in:4.73CVE-2023-28771derived from NVD
zywall usg 310 firmwareNVD
Affected:>= 4.60, < 4.73Fixed in:4.73CVE-2023-28771derived from NVD

TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works

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 RequiredNone
User InteractionNone
ScopeUnchanged

Impact

ConfidentialityHigh
IntegrityHigh
AvailabilityHigh

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

Exploit Intelligence

99.28%probability of exploitation in 30 days
100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

Zyxel Multiple Firewalls OS Command Injection Vulnerability

Zyxel ATP, USG FLEX, VPN, and ZyWALL/USG firewalls allow for improper error message handling which could allow an unauthenticated attacker to execute OS commands remotely by sending crafted packets to an affected device.

Apply updates per vendor instructions.

Remediation due: 2023-06-21

References

Vendor Advisory1
Government Resource1

Related Vulnerabilities

Other CWE-78 (OS Command Injection) vulnerabilities, ordered by exploit likelihood. View all

CVESeverityCVSSEPSSExploitedFix
CVE-2021-1498Critical9.8100%KEVFix
CVE-2014-6271Critical9.8100%KEVFix
CVE-2019-16920Critical9.8100%KEV-
CVE-2022-44877Critical9.8100%KEVFix
CVE-2020-8515Critical9.8100%KEV-
CVE-2020-9054Critical9.8100%KEVFix
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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 2025-10-27.