CVE-2019-25401: Bematech MP-4200 TH Printer DoS Flaw

CVE-2019-25401 Overview

CVE-2019-25401 is a denial of service vulnerability affecting the Bematech (formerly Logic Controls, now Elgin) MP-4200 TH thermal receipt printer. The vulnerability exists in the admin configuration page of the printer's embedded web interface. Remote attackers can send crafted POST requests with malformed admin and person parameters to crash the printer's web service, causing a denial of service condition that disrupts printer operations.

Critical Impact

Remote attackers can crash the printer's web service without authentication, causing service disruption to point-of-sale and receipt printing operations.

Affected Products

• Bematech MP-4200 TH Thermal Receipt Printer
• Logic Controls MP-4200 TH Thermal Receipt Printer (rebranded)
• Elgin MP-4200 TH Thermal Receipt Printer (current branding)

Discovery Timeline

• 2026-02-18 - CVE CVE-2019-25401 published to NVD
• 2026-02-19 - Last updated in NVD database

Technical Details for CVE-2019-25401

Vulnerability Analysis

This vulnerability is classified as CWE-400 (Uncontrolled Resource Consumption), a type of resource exhaustion flaw that allows attackers to consume system resources in an uncontrolled manner. The embedded web server on the MP-4200 TH printer fails to properly validate and handle malformed input in the admin and person parameters submitted to the configuration page.

When specially crafted POST requests are sent to the admin configuration endpoint, the printer's web service cannot properly process the malformed data, leading to a crash condition. Since the attack vector is network-based and requires no authentication or user interaction, any attacker with network access to the printer can exploit this vulnerability to disrupt printing operations.

The impact is primarily availability-focused, as the vulnerability does not allow for data exfiltration or system compromise, but it can significantly disrupt business operations in retail and hospitality environments where receipt printers are critical infrastructure.

Root Cause

The root cause of CVE-2019-25401 is improper input validation in the printer's embedded web server. The application fails to implement adequate bounds checking and input sanitization for the admin and person parameters in the configuration interface. When these parameters contain unexpected or malformed data, the web service enters an error state that results in service termination rather than graceful error handling.

Attack Vector

The attack is conducted over the network against the printer's web administration interface. An attacker sends HTTP POST requests to the admin configuration page with specially crafted values in the admin and person parameters. The malformed input triggers uncontrolled resource consumption or an unhandled exception in the web service, causing it to crash. No authentication is required to exploit this vulnerability, making it particularly dangerous in environments where printers are accessible on the local network.

The vulnerability can be exploited by sending malformed POST requests to the printer's configuration endpoint. Technical details and proof-of-concept information can be found in the Exploit-DB #47648 entry and the VulnCheck Advisory.

Detection Methods for CVE-2019-25401

Indicators of Compromise

• Unexpected printer web service crashes or restarts
• Unusual HTTP POST traffic to the printer's admin configuration page
• Multiple POST requests containing abnormally long or malformed admin and person parameters
• Network logs showing repeated connection attempts to the printer's web interface from unexpected sources

Detection Strategies

• Monitor network traffic for HTTP POST requests to printer administration endpoints
• Implement intrusion detection rules to identify malformed parameters in requests to the printer
• Configure alerts for printer service unavailability or repeated restart events
• Review web server logs on the printer for error conditions related to parameter parsing

Monitoring Recommendations

• Enable logging on network firewalls for traffic to printer management interfaces
• Deploy network monitoring to track unusual traffic patterns targeting IoT and embedded devices
• Implement availability monitoring for critical receipt printers to detect service disruptions
• Segment printer networks to limit exposure and simplify traffic monitoring

How to Mitigate CVE-2019-25401

Immediate Actions Required

• Restrict network access to the printer's web administration interface using firewall rules
• Place printers on isolated network segments with limited access from untrusted networks
• Disable the web administration interface if not required for operations
• Monitor for unusual network activity targeting printer devices

Patch Information

No official vendor patch information is currently available for this vulnerability. Organizations should contact the printer vendor (Elgin/Bematech) for firmware update availability. Additional technical details are available in the VulnCheck Advisory on Bematech Printer and the Legacy Global Product Page.

Workarounds

• Configure network ACLs to restrict access to the printer's web interface to trusted management stations only
• Implement a firewall rule to block external access to the printer's HTTP port (typically port 80)
• Consider deploying a reverse proxy with input validation in front of printer management interfaces
• If the web interface is not needed, disable it through the printer's local configuration menu

# Example firewall rule to restrict printer web interface access (iptables)
# Replace PRINTER_IP with the actual printer IP address
# Replace MANAGEMENT_IP with trusted management station IP

iptables -A INPUT -p tcp -d PRINTER_IP --dport 80 -s MANAGEMENT_IP -j ACCEPT
iptables -A INPUT -p tcp -d PRINTER_IP --dport 80 -j DROP