CVE-2024-11253 – This CVE describes a post-authentication comman... (How to Fix)

Q: What is the severity of CVE-2024-11253?

CVE-2024-11253 has a CVSS score of 7.2 (HIGH). This CVE describes a post-authentication command injection vulnerability in Zyxel VMG8825-T50K devices. An authenticated attacker with administrator privileges can execute arbitrary operating system commands on vulnerable devices. This affects Zyxel VMG8825-T50K firmware versions V5.50(ABOM.8.5)C0 and earlier.

📋 TL;DR

This CVE describes a post-authentication command injection vulnerability in Zyxel VMG8825-T50K devices. An authenticated attacker with administrator privileges can execute arbitrary operating system commands on vulnerable devices. This affects Zyxel VMG8825-T50K firmware versions V5.50(ABOM.8.5)C0 and earlier.

💻 Affected Systems

Products:

Zyxel VMG8825-T50K

Versions: V5.50(ABOM.8.5)C0 and earlier

Operating Systems: Zyxel proprietary firmware

Default Config Vulnerable: ⚠️ Yes

Notes: Requires administrator privileges to access diagnostic function with DNSServer parameter.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete device compromise allowing attacker to install persistent backdoors, pivot to internal networks, steal credentials, or use device as part of botnet.

🟠

Likely Case

Attacker with legitimate admin credentials or stolen credentials executes commands to reconfigure device, intercept traffic, or disable security features.

🟢

If Mitigated

With proper access controls and network segmentation, impact limited to single device with no lateral movement.

🌐 Internet-Facing: MEDIUM - Requires admin authentication but many devices have web interfaces exposed to internet with default credentials.

🏢 Internal Only: HIGH - Internal attackers with admin access or compromised credentials can exploit this vulnerability.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ✅ No

Complexity: MEDIUM

Requires admin credentials but command injection is straightforward once authenticated.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Versions after V5.50(ABOM.8.5)C0

Vendor Advisory: https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-post-authentication-command-injection-vulnerabilities-in-certain-dsl-ethernet-cpe-fiber-ont-and-wifi-extender-devices-03-11-2025

Restart Required: No

Instructions:

1. Log into device web interface. 2. Navigate to System > Firmware Upgrade. 3. Download latest firmware from Zyxel support site. 4. Upload and apply firmware update. 5. Verify version is updated.

🔧 Temporary Workarounds

Restrict Admin Access

all

Limit administrative access to trusted IP addresses only

Configure firewall rules to restrict web interface access to specific IP ranges

Disable Unused Diagnostic Features

all

Disable diagnostic functions if not required

Navigate to Maintenance > Diagnostics and disable unused diagnostic tools

🧯 If You Can't Patch

Change all default admin credentials to strong, unique passwords
Segment device on isolated network VLAN to limit lateral movement

🔍 How to Verify

Check if Vulnerable:

Check firmware version in web interface under System > Status > Firmware Version

Check Version:

ssh admin@device-ip 'cat /proc/version' or check web interface

Verify Fix Applied:

Verify firmware version is newer than V5.50(ABOM.8.5)C0

📡 Detection & Monitoring

Log Indicators:

Unusual command execution in system logs
Multiple failed login attempts followed by successful admin login
Unexpected configuration changes to DNSServer settings

Network Indicators:

Unusual outbound connections from device
Traffic to unexpected DNS servers
SSH or telnet connections from device to internal systems

SIEM Query:

source="zyxel-logs" AND (event="command_execution" OR event="config_change" AND parameter="DNSServer")

📊 Metadata

CVE ID: CVE-2024-11253

CVSS v3 Score: 7.2 (HIGH)

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

CWE: CWE-78

EPSS Score: 0.32% exploit probability (54.4th percentile)

Published: March 11, 2025

Last Updated: January 13, 2026

🔗 References

https://www.zyxel.com/global/en/support/security-advisories/zyxel-security-advisory-for-post-authentication-command-injection-vulnerabilities-in-certain-dsl-ethernet-cpe-fiber-ont-and-wifi-extender-devices-03-11-2025 Vendor Advisory

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