CVE-2025-53869 identifies a security vulnerability in multiple multifunction printers (MFPs) manufactured by Brother Industries, Ltd. The core issue is improper validation of server certificates by these devices. Normally, MFPs validate server certificates to ensure secure communication with trusted servers, relying on a set of root certificates to verify authenticity. Due to this flaw, an attacker positioned as a man-in-the-middle (MitM) on the network can exploit the improper validation mechanism to replace the device’s root certificate store with a set of arbitrary certificates. This replacement undermines the device’s trust model, allowing the attacker to intercept, decrypt, or manipulate communications that the device believes are secure. The vulnerability has a CVSS v3.1 base score of 3.7, categorized as low severity. The vector indicates network attack (AV:N), high attack complexity (AC:H), no privileges required (PR:N), no user interaction (UI:N), unchanged scope (S:U), no confidentiality impact (C:N), limited integrity impact (I:L), and no availability impact (A:N). The high attack complexity suggests that exploitation requires specific conditions, such as network positioning and possibly additional constraints. No known exploits have been reported in the wild, and the vendor has not yet provided detailed patch information. The affected versions are unspecified and require consultation of vendor advisories. This vulnerability primarily threatens the integrity of communications and trust in secure connections established by the MFPs, potentially enabling further attacks such as data interception or injection of malicious content during print jobs or device management.

For European organizations, the impact of CVE-2025-53869 is primarily on the integrity of communications involving Brother MFPs. Although the confidentiality and availability impacts are minimal, the ability of an attacker to replace root certificates could facilitate man-in-the-middle attacks, allowing interception or manipulation of sensitive data transmitted to or from the device. This risk is particularly relevant in environments where MFPs are connected to less secure or segmented networks, such as public or guest networks, or where network monitoring is insufficient. Organizations handling sensitive documents or operating in regulated sectors (e.g., finance, healthcare, government) may face compliance and reputational risks if such interception occurs. However, the high attack complexity and lack of known exploits reduce the immediate threat level. The vulnerability could also be leveraged as a stepping stone for more advanced attacks targeting network infrastructure or internal systems. European entities relying heavily on Brother MFPs for document processing and networked printing should assess their exposure and consider the potential for targeted attacks exploiting this flaw.

To mitigate CVE-2025-53869, European organizations should first consult Brother Industries’ official advisories and apply any available firmware updates or patches promptly once released. In the absence of patches, network-level controls should be implemented to restrict access to MFP management interfaces and communication ports, limiting exposure to trusted network segments only. Employ network segmentation to isolate MFPs from untrusted or public networks, reducing the risk of man-in-the-middle positioning. Use network monitoring and intrusion detection systems to identify unusual certificate changes or suspicious network activity involving MFPs. Where possible, enforce strict TLS configurations and certificate pinning on devices communicating with the MFPs to detect unauthorized certificate replacements. Additionally, organizations should review and harden device configurations, disable unnecessary services, and maintain an inventory of affected devices to prioritize remediation efforts. Training IT staff to recognize signs of certificate tampering and ensuring incident response plans include scenarios involving MFP compromise will enhance preparedness.