CVE-2022-41926 is a medium-severity vulnerability affecting Nextcloud Talk Android versions prior to 14.1.0. Nextcloud Talk is a chat and communication system integrated into the Nextcloud ecosystem, with the Android implementation allowing users to communicate via messages and calls. The vulnerability arises from an incorrect permission assignment related to the broadcast receiver component within the Android app. Specifically, the receiver is not protected by the required broadcastPermission, which means that any malicious app installed on the same device can register to receive broadcasts intended for Nextcloud Talk. This lack of protection violates the principle of least privilege and allows unauthorized apps to monitor communication data being broadcast internally by the Nextcloud Talk app. The vulnerability is categorized under CWE-732 (Incorrect Permission Assignment for Critical Resource) and CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor), indicating that sensitive communication data can be exposed due to improper permission controls. Exploitation does not require elevated privileges beyond installing a malicious app on the same Android device, and no user interaction beyond app installation is necessary. There are no known workarounds, and the only remediation is upgrading Nextcloud Talk Android to version 14.1.0 or later, where the broadcast receiver is properly protected by broadcastPermission, preventing unauthorized interception of communication broadcasts. No exploits have been observed in the wild as of the publication date (November 25, 2022).

For European organizations using Nextcloud Talk Android clients, this vulnerability could lead to unauthorized disclosure of sensitive communication data. Since Nextcloud is widely adopted by enterprises, public institutions, and private users across Europe for secure collaboration, the exposure of chat messages or call metadata could compromise confidentiality and privacy. This is particularly critical for sectors handling sensitive information such as government agencies, healthcare providers, financial institutions, and legal firms. An attacker with a malicious app on a user's device could silently monitor conversations, potentially leading to data leaks, espionage, or reputational damage. Although the vulnerability does not allow direct modification or disruption of communications (integrity and availability impacts are limited), the confidentiality breach alone can have significant consequences, especially under stringent European data protection regulations like GDPR. The ease of exploitation (requiring only app installation) increases the risk, particularly in environments where users may install unvetted applications. However, the scope is limited to Android devices running vulnerable versions of Nextcloud Talk, and the attacker must have physical or remote access to install malicious apps on the device.

1. Immediate upgrade of all Nextcloud Talk Android clients to version 14.1.0 or later to ensure the broadcast receiver is properly protected. 2. Implement mobile device management (MDM) solutions to restrict installation of unauthorized or untrusted applications on corporate Android devices, reducing the risk of malicious app installation. 3. Educate users on the risks of installing apps from untrusted sources and enforce the use of official app stores with security vetting. 4. Monitor Android devices for unusual app behavior or unauthorized broadcast receivers that could indicate exploitation attempts. 5. For organizations with high-security requirements, consider deploying endpoint detection and response (EDR) tools capable of detecting inter-app communication anomalies. 6. Regularly audit and update mobile applications and their permissions to ensure compliance with security best practices. 7. Coordinate with Nextcloud administrators to ensure server-side configurations and policies support secure client communications and timely updates.