CVE-2026-5115: PaperCut NG/MF Information Disclosure Flaw

CVE-2026-5115 Overview

CVE-2026-5115 is a session hijacking vulnerability affecting the PaperCut NG/MF embedded application for Konica Minolta devices. The PaperCut NG/MF Embedded application is a software interface that runs directly on the touch screen of multi-function devices, providing print management capabilities.

The vulnerability was internally discovered, revealing that the communication channel between the embedded application and the server was insecure. This insecure channel could leak data including sensitive information that may be used to mount an attack on the device. Such an attack could potentially be used to steal data or to perform a phishing attack on the end user.

Critical Impact

Attackers on an adjacent network could potentially intercept sensitive session data transmitted between the embedded application and the PaperCut server, enabling session hijacking, data theft, or phishing attacks targeting end users.

Affected Products

• PaperCut NG (Embedded application for Konica Minolta devices)
• PaperCut MF (Embedded application for Konica Minolta devices)
• Konica Minolta multi-function devices running PaperCut embedded application

Discovery Timeline

• 2026-03-31 - CVE-2026-5115 published to NVD
• 2026-04-01 - Last updated in NVD database

Technical Details for CVE-2026-5115

Vulnerability Analysis

This vulnerability is classified under CWE-319 (Cleartext Transmission of Sensitive Information). The core issue lies in the insecure communication channel between the PaperCut embedded application running on Konica Minolta device touch screens and the PaperCut server infrastructure.

The embedded application transmits session data and potentially other sensitive information without adequate protection, making it susceptible to interception by attackers with adjacent network access. While the attack requires adjacency to the network and user interaction, successful exploitation could result in high confidentiality impact to both the vulnerable system and subsequent downstream systems.

Root Cause

The root cause stems from the lack of proper encryption or secure transport protocols in the communication channel between the PaperCut embedded application and the server. This cleartext transmission (CWE-319) allows sensitive session tokens and user data to be captured by malicious actors who have access to the adjacent network segment where these communications occur.

Attack Vector

The attack requires the adversary to be positioned on an adjacent network (such as the same local network segment as the multi-function device). The attacker must be able to intercept network traffic between the embedded application and the PaperCut server. User interaction is required for exploitation, which may involve a user authenticating or performing actions on the device while the attacker is actively monitoring network traffic.

The captured session information could then be used to hijack the user's session, steal sensitive print job data, or conduct targeted phishing attacks against the end user by impersonating legitimate PaperCut communications.

Detection Methods for CVE-2026-5115

Indicators of Compromise

• Unusual network traffic patterns between Konica Minolta devices and PaperCut servers, particularly unencrypted communications
• Evidence of ARP spoofing or man-in-the-middle positioning attempts targeting the network segment containing multi-function devices
• Unexpected session activity or authentication anomalies in PaperCut server logs

Detection Strategies

• Monitor network traffic for cleartext communications between embedded devices and PaperCut servers
• Implement network intrusion detection rules to identify potential session token interception attempts on the local network segment
• Review PaperCut server authentication logs for anomalous session behaviors or concurrent sessions from different network locations

Monitoring Recommendations

• Deploy network segmentation monitoring to detect unauthorized access to the network segment containing print devices
• Enable verbose logging on PaperCut servers and correlate with network flow data
• Implement endpoint detection on systems that interact with print management infrastructure

How to Mitigate CVE-2026-5115

Immediate Actions Required

• Review the PaperCut Security Bulletin March 2026 for specific remediation guidance
• Isolate affected Konica Minolta devices on a dedicated network segment with restricted access
• Audit current network access controls surrounding print infrastructure
• Consider temporarily disabling the embedded application until a patch can be applied

Patch Information

PaperCut has released security information regarding this vulnerability in their March 2026 Security Bulletin. Organizations should consult the PaperCut Security Bulletin March 2026 for detailed patch information and update instructions specific to their deployment configuration.

Workarounds

• Implement network segmentation to isolate multi-function devices from untrusted network segments
• Enable VPN or other encrypted tunneling for communications between embedded applications and PaperCut servers where possible
• Restrict physical and network access to areas containing affected Konica Minolta devices
• Monitor for suspicious network activity and implement intrusion detection on the affected network segment