What is the CVSS score of CVE-2023-22913?

CVE-2023-22913 has a CVSS 3.1 base score of 8.1 (High). CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H. EPSS exploitation probability: 1.3%.

Vpn50 Firmware CVE-2023-22913

HIGH

Command Injection (CWE-77)

2023-04-24 security@zyxel.com.tw

Command Injection Zyxel Vpn50 Firmware Vpn100 Firmware Vpn300 Firmware Vpn1000 Firmware Usg Flex 100 Firmware Usg Flex 100W Firmware Usg Flex 200 Firmware Usg Flex 500 Firmware Usg Flex 700 Firmware Usg Flex 50W Firmware Usg Flex 50 Firmware

8.1

CVSS 3.1 · NVD

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Vulnerability Assessment

Weakness	CWE CWE-77 OWASP Top 10:2025 A05:2025 - Injection ASVS 5.0 V1 - Encoding and Sanitization Command injection prevention MITRE ATT&CK 1 technique across 1 tactic: Execution The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up. Sign in to read
Impact	CVSS score of 8.1 (HIGH). Attack characteristics: network attack vector, low complexity, low privileges required, no user interaction not required.
Exploit ScenarioDerived	A remote attacker could inject arbitrary commands into system command execution by sending crafted requests to the affected application.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).

No patch listed yet 1.3% exploitation probability (EPSS)

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AnalysisAI

A post-authentication command injection vulnerability in the “account_operator.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, and VPN series firmware versions 4.30. Rated high severity (CVSS 8.1), this vulnerability is remotely exploitable, low attack complexity. No vendor patch available.

RemediationAI

No vendor patch is available at time of analysis. Monitor vendor advisories for updates. Use parameterized APIs, avoid shell execution, validate input with strict allowlists.

Affects your stack

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Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability is classified as Command Injection (CWE-77), which allows attackers to inject arbitrary commands into system command execution. A post-authentication command injection vulnerability in the “account_operator.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote authenticated attacker to modify device configuration data, resulting in denial-of-service (DoS) conditions on an affected device. Affected products include: Zyxel Usg Flex 100 Firmware, Zyxel Usg Flex 100W Firmware, Zyxel Usg Flex 200 Firmware, Zyxel Usg Flex 50 Firmware, Zyxel Usg Flex 50W Firmware. Version information: through 5.35.

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Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.1 HIGH

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

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector

Network

Attack Complexity

Low

Privileges Required

Low

User Interaction

None

Scope

Unchanged

Confidentiality

None

Integrity

High

Availability

High

DescriptionNVD

A post-authentication command injection vulnerability in the “account_operator.cgi” CGI program of Zyxel USG FLEX series firmware versions 4.50 through 5.35, and VPN series firmware versions 4.30 through 5.35, which could allow a remote authenticated attacker to modify device configuration data, resulting in denial-of-service (DoS) conditions on an affected device.

Threat Intelligence Overview

EPSS Score

1.3%

Top 33% exploitable

Data Quality

2 sources

Confidence: Low

NVD

CVE.org

EPSS

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue

Severity HIGH

CISA KEV No

Public POC No

EPSS 1.3%

Patch available No

Active threat No

Deciding rule

HIGH severity (CVSS 7.0-8.9)

What every action level means

Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.

Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.

This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.

This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.

Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived

Scheduled

Exploitation· derived

None

System Exposure· derived

Open

Automatable· derived

Human Impact· derived

Medium

Priority Score

Low Medium High Critical

KEV: 0

EPSS: +1

CVSS: +40

PoC: 0

Weaponized: 0

Threat intel: 0

Gov advisory: 0

Attack Technique

OS Command Injection CRITICAL

OS command injection occurs when an application passes unsanitized user input directly into system shell commands.

Affected Products (CPE)NVD

cpe:2.3:o:zyxel:usg_flex_100_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg_flex_100w_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg_flex_200_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg_flex_50_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg_flex_50w_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg_flex_500_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:usg_flex_700_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:vpn100_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:vpn1000_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:vpn300_firmware:*:*:*:*:*:*:*:*

cpe:2.3:o:zyxel:vpn50_firmware:*:*:*:*:*:*:*:*

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Same weakness CWE-77 – Command Injection

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References

Advisories & patches

ADVISORY https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-multiple-vulnerabilities-of-firewalls-and-aps

Search Externally

GitHub PoC

Exploit-DB PacketStorm Snyk Rapid7 Nuclei Templates Trickest PoC

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