CVE-2025-55704: Brother MFPs Information Disclosure Flaw

CVE-2025-55704 Overview

CVE-2025-55704 is a hidden functionality vulnerability (CWE-912) affecting multiple multifunction printers (MFPs) manufactured by Brother Industries, Ltd. This vulnerability allows an unauthenticated attacker to access logs from the affected devices over the network and potentially obtain sensitive information contained within those logs.

The vulnerability stems from undocumented functionality present in the device firmware that exposes internal logging mechanisms without proper authentication controls. Organizations using affected Brother MFPs in their environments should evaluate their exposure and apply available mitigations.

Critical Impact

Attackers can remotely access device logs containing potentially sensitive information without authentication, enabling reconnaissance and data exfiltration from enterprise printing infrastructure.

Affected Products

• Multiple Brother Industries MFP (Multifunction Printer) models
• Related Konica Minolta devices (per security advisory)
• Specific model lists available in vendor security advisories

Discovery Timeline

• 2026-01-29 - CVE CVE-2025-55704 published to NVD
• 2026-01-29 - Last updated in NVD database

Technical Details for CVE-2025-55704

Vulnerability Analysis

This vulnerability is classified under CWE-912 (Hidden Functionality), indicating that the affected Brother MFPs contain undocumented functionality that was not intended to be accessible to end users or external parties. Hidden functionality vulnerabilities often arise from debugging features, maintenance interfaces, or test code that remains in production firmware.

The vulnerability is exploitable over the network without requiring any authentication or user interaction. An attacker with network access to the affected MFP can leverage this hidden functionality to retrieve device logs. These logs may contain sensitive information such as user account names, document metadata, network configuration details, internal IP addresses, and potentially other organizational data processed by the printing device.

The attack surface is particularly concerning in enterprise environments where MFPs are often deployed on internal networks with access to sensitive document workflows and may not receive the same security scrutiny as traditional computing endpoints.

Root Cause

The root cause of CVE-2025-55704 is the presence of hidden functionality within the firmware of affected Brother MFPs. This undocumented feature allows log retrieval without implementing proper access controls or authentication mechanisms. Such hidden functionality typically originates from:

• Development or debugging interfaces left in production firmware
• Maintenance features intended for service technicians but accessible remotely
• Insufficient access control implementation around logging subsystems
• Legacy code that was not removed during the firmware development lifecycle

Attack Vector

The attack is network-based, meaning an attacker must have network connectivity to the vulnerable MFP. No authentication credentials are required, and no user interaction is necessary for exploitation. The attacker can directly access the hidden functionality to retrieve logs.

In a typical attack scenario:

1. The attacker identifies a vulnerable Brother MFP on the network through scanning or enumeration
2. The attacker accesses the hidden functionality through the network interface
3. Device logs are retrieved without authentication
4. Sensitive information within the logs is extracted and potentially used for further attacks

The information obtained could facilitate additional attacks such as credential harvesting, network mapping, or social engineering based on document and user information contained in the logs.

Detection Methods for CVE-2025-55704

Indicators of Compromise

• Unusual or unexpected network connections to MFP devices from unknown sources
• Abnormal log access patterns or requests to the MFP management interface
• Network traffic to MFPs from hosts that do not typically interact with printing services
• Evidence of log file retrieval in network traffic captures

Detection Strategies

• Implement network monitoring to detect unusual traffic patterns to MFP devices
• Enable audit logging on network infrastructure to track connections to printing devices
• Use endpoint detection and response (EDR) solutions like SentinelOne to monitor for reconnaissance activity targeting network devices
• Deploy network segmentation monitoring to identify cross-segment access attempts to printer VLANs

Monitoring Recommendations

• Monitor network flows to and from MFP devices for anomalous connection patterns
• Implement alerting for any access to MFP management interfaces from non-administrative workstations
• Review MFP device logs regularly for signs of unauthorized access attempts
• Consider deploying network detection capabilities on segments where MFPs are located

How to Mitigate CVE-2025-55704

Immediate Actions Required

• Review the Brother Support FAQ for affected model lists and available firmware updates
• Consult the JVN Security Advisory for technical details and mitigation guidance
• Isolate affected MFPs on a dedicated network segment with restricted access
• Implement firewall rules to limit network access to MFPs to only authorized systems and users
• Disable unnecessary network services on affected devices where possible

Patch Information

Brother Industries has released information regarding this vulnerability. Organizations should consult the following resources for firmware updates and specific remediation guidance:

• Brother Support FAQ - Official vendor guidance
• JVN Security Advisory - Japanese vulnerability coordination center advisory
• Konica Minolta Security Advisory - Related advisory for Konica Minolta devices

Check with your device's specific model to determine if firmware updates are available that address this vulnerability.

Workarounds

• Place MFPs on isolated network segments with restricted access from general user networks
• Implement access control lists (ACLs) on network infrastructure to limit connectivity to MFPs
• Disable remote management interfaces where not required for operations
• Use network firewalls to restrict inbound connections to MFPs to only necessary services and authorized IP addresses
• Consider implementing 802.1X network access control for printer network segments

# Example network segmentation firewall rule (iptables)
# Restrict access to MFP subnet to only authorized management hosts
iptables -A FORWARD -s 10.0.0.0/24 -d 192.168.100.0/24 -j DROP
iptables -A FORWARD -s 10.10.10.5 -d 192.168.100.0/24 -j ACCEPT
# Replace IP ranges with your specific network configuration