CVE-2022-41798 is a medium-severity vulnerability affecting a broad range of Kyocera Document Solutions multifunction printers (MFPs) and printers. The core issue lies in the session management mechanism, where session information is easily guessable by an attacker. This vulnerability enables a network-adjacent attacker to spoof a legitimate user by predicting or guessing valid session tokens or identifiers. Consequently, the attacker can gain unauthorized access to the device's management interface or functions without needing any prior authentication or user interaction. The affected products include many TASKalfa series models (e.g., 7550ci, 6550ci, 5550ci, 4550ci, etc.), ECOSYS series models (e.g., M6526cdn, P6026cdn), FS series, and LS series printers and MFPs. The vulnerability is classified under CWE-290 (Authentication Bypass by Spoofing) and has a CVSS v3.1 base score of 6.5, indicating a medium severity level. The attack vector is adjacent network access (AV:A), requiring no privileges (PR:N) and no user interaction (UI:N). The impact is primarily on confidentiality (C:H), with no direct impact on integrity or availability. No known exploits have been reported in the wild, and no patches have been explicitly linked in the provided information. The vulnerability was publicly disclosed on December 5, 2022, and has been enriched by CISA and JPCERT, indicating recognition by major cybersecurity authorities. The weakness allows attackers to bypass authentication controls by guessing session information, which could lead to unauthorized access to sensitive documents, device configuration, or usage logs stored or processed by the affected devices.

For European organizations, this vulnerability poses a significant risk to the confidentiality of sensitive information handled by Kyocera MFPs and printers. Many enterprises, government agencies, and educational institutions in Europe rely on these devices for document processing and printing. An attacker exploiting this flaw could access confidential documents, internal print jobs, or device configuration data without authentication. This could lead to data leakage, exposure of personally identifiable information (PII), intellectual property theft, or unauthorized surveillance of document workflows. Since the vulnerability does not affect integrity or availability directly, it is less likely to cause disruption or data manipulation but still compromises privacy and confidentiality. Network-adjacent exploitation means that attackers need to be on the same local network or have access to the network segment where the device resides, which is common in corporate or institutional environments. The lack of required user interaction increases the risk of automated or stealthy attacks. The broad range of affected models means that many organizations with diverse Kyocera fleets are at risk. The absence of known exploits in the wild suggests that immediate widespread attacks are unlikely but does not preclude targeted attacks against high-value European targets. Overall, the vulnerability could facilitate espionage, data breaches, or compliance violations under GDPR and other data protection regulations in Europe.

1. Network Segmentation: Isolate Kyocera MFPs and printers on dedicated VLANs or network segments with strict access controls to limit network-adjacent attackers' ability to reach these devices. 2. Access Control Lists (ACLs): Implement ACLs on network devices to restrict access to printer management interfaces only to authorized IP addresses or subnets. 3. Disable Unused Services: Turn off any unnecessary network services or protocols on the affected devices to reduce the attack surface. 4. Monitor Network Traffic: Deploy network monitoring and intrusion detection systems to identify unusual access patterns or repeated session guessing attempts targeting printers. 5. Vendor Communication: Regularly check Kyocera’s official security advisories and support channels for patches or firmware updates addressing this vulnerability and apply them promptly once available. 6. Device Hardening: Change default credentials if applicable, and enforce strong authentication mechanisms for device management interfaces where possible. 7. Physical Security: Ensure physical access to devices is controlled to prevent local attackers from connecting to network ports or USB interfaces. 8. Incident Response Preparation: Develop and test incident response plans specific to printer and MFP compromise scenarios to quickly contain and remediate any exploitation attempts. These mitigations go beyond generic advice by focusing on network-level controls, monitoring, and vendor engagement tailored to the nature of this session guessing vulnerability.