CVE-2025-40836 is a high-severity vulnerability identified in the Ericsson Indoor Connect 8855 device, which is a product designed to enhance indoor cellular coverage. The vulnerability stems from improper input validation (CWE-20), a common software weakness where the system fails to correctly verify or sanitize input data before processing it. This flaw allows an attacker to craft malicious input that can lead to command execution with escalated privileges on the affected device. The CVSS 4.0 base score of 8.7 reflects the critical nature of this vulnerability, highlighting that it can be exploited remotely (AV:N) without user interaction (UI:N) or authentication (AT:N), and requires low attack complexity (AC:L). The vulnerability impacts confidentiality, integrity, and availability at a high level (VC:H, VI:H, VA:H), meaning an attacker could potentially gain full control over the device, manipulate data, disrupt services, or pivot to other network segments. The affected product, Ericsson Indoor Connect 8855, is typically deployed in enterprise, public venues, and critical infrastructure environments to improve cellular connectivity indoors. Given the device’s role in network infrastructure, exploitation could lead to significant operational disruptions and security breaches. No known exploits are currently reported in the wild, and no patches have been published yet, indicating that organizations must proactively prepare for mitigation once updates become available. The vulnerability was reserved in April 2025 and published in September 2025, suggesting recent discovery and disclosure.

For European organizations, the impact of this vulnerability could be substantial, especially for those relying on Ericsson Indoor Connect 8855 devices to maintain indoor cellular coverage in offices, hospitals, transportation hubs, and other critical facilities. Successful exploitation could allow attackers to execute arbitrary commands with escalated privileges, potentially leading to unauthorized access to sensitive communications, disruption of cellular services, and lateral movement within corporate or public networks. This could affect business continuity, data privacy compliance (e.g., GDPR), and critical infrastructure resilience. Given the device’s integration in communication networks, attacks could also undermine emergency services or public safety communications. The lack of authentication and user interaction requirements increases the risk of automated or remote exploitation, making it a pressing concern for network security teams across Europe.

1. Immediate Network Segmentation: Isolate Ericsson Indoor Connect 8855 devices from general network access, restricting management interfaces to trusted administrative networks only. 2. Access Control Hardening: Implement strict firewall rules and access control lists (ACLs) to limit exposure of the device’s management ports to the internet or untrusted networks. 3. Monitoring and Logging: Enable detailed logging on the devices and monitor for unusual command execution patterns or network traffic anomalies indicative of exploitation attempts. 4. Vendor Coordination: Engage with Ericsson support to obtain timelines for official patches or firmware updates addressing CVE-2025-40836 and apply them promptly upon release. 5. Incident Response Preparedness: Develop and rehearse incident response plans specific to network infrastructure compromise, including rapid isolation and forensic analysis of affected devices. 6. Configuration Review: Audit device configurations to disable any unnecessary services or interfaces that could be leveraged by attackers. 7. Threat Intelligence Sharing: Participate in industry and governmental cybersecurity information sharing platforms to stay informed about emerging exploits or mitigation techniques related to this vulnerability.