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Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization OS command sanitization, avoid shell exec
MITRE ATT&CK

2 techniques across 1 tactic: Execution

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Impact

High risk (CVSS 8.8). Unsupported EOL device with no patch available. Default/weak credentials commonly used on legacy DSL modems amplify the risk.

Exploit ScenarioDerived

Attackers use default credentials to authenticate, then inject OS commands through the web interface to install persistent backdoors or recruit the device into a botnet.

Act Now Prioritize within 24-48h. Why: HIGH severity + EPSS > 10%.
Exploited in the wild (CISA KEV) No patch listed yet 45.9% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 28, 2026

Zyxel VMG4325-B10A legacy DSL CPE contains post-authentication OS command injection in the CGI program, allowing authenticated attackers to execute OS commands via crafted HTTP POST requests. No patch available (EOL device).

Earlier versions of this analysis (1)
v1 Mar 28, 2026 - 18:24 CVSS 8.8

A post-authentication command injection in Zyxel VMG4325-B10A's CGI web interface allows authenticated attackers to execute OS commands. The device is unsupported and will not receive patches.

RemediationAI

Replace the EOL device. If impossible, change default credentials, restrict management access to local network only.

Affects your stack

Find out whether the stacks and servers you run are on an affected version.

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

Technical ContextAI · show details

The CWE-78 command injection in the CGI handler passes user input from HTTP POST parameters to shell commands without proper sanitization.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.8 HIGH
AV:N/AC:L/PR:L/UI:N/S:U/C:H/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
High
Integrity
High
Availability
High

Lifecycle Timeline

2
Added to CISA KEV
Oct 27, 2025 - 17:04 cisa
CISA KEV
CVE Published
Feb 04, 2025 - 10:15 nvd
HIGH 8.8

DescriptionCVE.org

UNSUPPORTED WHEN ASSIGNED A post-authentication command injection vulnerability in the CGI program of the legacy DSL CPE Zyxel VMG4325-B10A firmware version 1.00(AAFR.4)C0_20170615 could allow an authenticated attacker to execute operating system (OS) commands on an affected device by sending a crafted HTTP POST request.

Executive ViewAI

Why It Matters

Organizations using the CGI program of the legacy DSL CPE Zyxel VMG4325-B10A firmware face significant risk from CVE-2024-40890, a OS command injection vulnerability rated CVSS 8.8. Successful exploitation could allow attackers to execute arbitrary code or commands on affected systems, potentially leading to full system compromise. This vulnerability is actively exploited in the wild (KEV-listed) and requires immediate remediation. Immediate patching is required per CISA KEV mandate.

Business Impact: Severe
Compensating Controls

Apply vendor patch. If immediate patching is not feasible: (1) Deploy WAF rules to block injection patterns; (2) Restrict network access to affected components; (3) Enable enhanced logging for suspicious activity.

Threat Intelligence Overview

EPSS Score
45.9%
Top 2% exploitable

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 Yes
Public POC No
EPSS 45.9%
Patch available No
Active threat Yes
Deciding rule
HIGH severity + EPSS > 10%
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
Immediate
Exploitation· derived
Active
System Exposure· derived
Open
Automatable· derived
No
Human Impact
Very High

Priority Score

140
Low Medium High Critical
KEV: +50
EPSS: +46
CVSS: +44
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

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

Affected Products (CPE)CVE.org

cpe:2.3:o:zyxel:vmg1312-b10a_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg1312-b10b_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg1312-b10e_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg3312-b10a_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg3313-b10a_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg3926-b10b_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg4325-b10a_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg4380-b10a_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg8324-b10a_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:vmg8924-b10a_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:sbg3300-n000_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:sbg3300-nb00_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:sbg3500-n000_firmware:-:*:*:*:*:*:*:*
cpe:2.3:o:zyxel:sbg3500-nb00_firmware:-:*:*:*:*:*:*:*

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