CVE-2025-11155 identifies a security vulnerability in the SATO S86-ex 203dpi device, specifically in version 61.00.00.09. The issue stems from the device's web server transmitting user credentials encoded only in base64 within HTTP headers during login. Base64 encoding is not a cryptographic mechanism but a simple encoding scheme that can be easily decoded by anyone intercepting the network traffic. This means that an attacker with network access could capture the HTTP requests containing these base64-encoded credentials and decode them to obtain plaintext usernames and passwords. The vulnerability is classified under CWE-261, which refers to weak encoding for sensitive information. According to the CVSS 4.0 vector, the attack vector is adjacent network (AV:A), requiring no privileges (PR:N), no user interaction (UI:A), and has a medium impact on confidentiality (VC:H) but no impact on integrity or availability. The scope is limited (SC:L), and there are no known exploits in the wild currently. The vulnerability arises because the device does not use stronger encryption or secure transport mechanisms (e.g., HTTPS with TLS) to protect credentials during transmission. This weakness could allow attackers to perform credential theft via network sniffing or man-in-the-middle attacks, potentially leading to unauthorized access to the device's web interface and subsequent control or information disclosure. The lack of available patches at the time of publication further increases the risk for users of the affected version.

For European organizations using the SATO S86-ex 203dpi device, this vulnerability poses a moderate security risk. The primary impact is the potential compromise of device credentials, which could lead to unauthorized access to the device's management interface. This could result in unauthorized configuration changes, leakage of sensitive operational data, or disruption of printing services. In environments where these devices are integrated into critical business workflows—such as logistics, manufacturing, or retail—the compromise could affect operational continuity and data confidentiality. Since the attack requires network proximity or access to the same network segment, organizations with segmented and well-controlled network environments may reduce exposure. However, in less segmented or poorly monitored networks, attackers could exploit this vulnerability to move laterally or escalate privileges. The medium CVSS score reflects that while the vulnerability does not directly impact system integrity or availability, the confidentiality breach could have cascading effects, especially if credentials are reused or if the device serves as a pivot point for further attacks. The absence of known exploits suggests limited current exploitation but does not preclude future attacks, especially as awareness of the vulnerability grows.

To mitigate this vulnerability, European organizations should implement the following specific measures: 1) Immediately restrict network access to the SATO S86-ex 203dpi devices to trusted and segmented network zones, minimizing exposure to untrusted users or networks. 2) Employ network-level encryption such as VPNs or IPsec tunnels when remote access to the device is necessary, ensuring credentials are not transmitted in clear or weakly encoded forms. 3) Monitor network traffic for unencrypted HTTP requests containing base64-encoded credentials and implement intrusion detection systems (IDS) rules to alert on suspicious login attempts or credential transmissions. 4) Where possible, configure the device to use HTTPS or other secure protocols for web management interfaces; if the device firmware does not support this, consider placing the device behind a secure reverse proxy that enforces TLS. 5) Enforce strong, unique passwords for device access and rotate them regularly to limit the window of opportunity if credentials are compromised. 6) Maintain an inventory of affected devices and track vendor communications for firmware updates or patches addressing this vulnerability. 7) Educate network administrators and security teams about the risks of weak credential encoding and the importance of network segmentation and encryption for device management interfaces.