CVE-2022-39210 is a medium-severity vulnerability affecting the Nextcloud Android client versions prior to 3.21.0. The issue stems from improper limitation of pathname to a restricted directory, classified under CWE-22 (Path Traversal). Specifically, the Nextcloud Android app does not adequately protect internal file paths, allowing an attacker or malicious app component to access internal files within the Nextcloud Android app's storage. This path traversal vulnerability can lead to unauthorized exposure of sensitive information stored within the app's internal directories, corresponding to CWE-200 (Exposure of Sensitive Information to an Unauthorized Actor). The vulnerability arises because the app fails to properly sanitize or restrict file path inputs, enabling traversal outside intended directories. Although no known exploits have been reported in the wild, the vulnerability poses a risk of data leakage, especially if sensitive user data or credentials are stored within the app's internal files. The issue requires no user interaction beyond having the vulnerable app installed, and exploitation does not require authentication beyond app access. The recommended remediation is to upgrade the Nextcloud Android client to version 3.21.0 or later, where the vulnerability has been addressed. No effective workarounds exist, making patching the primary mitigation strategy. Given the nature of the vulnerability, it primarily impacts confidentiality by potentially exposing sensitive data, while integrity and availability are less directly affected. The scope is limited to devices running the vulnerable Nextcloud Android client, and exploitation requires local access to the device or app context.

For European organizations, the impact of CVE-2022-39210 centers on potential data confidentiality breaches. Nextcloud is widely used across Europe, especially by enterprises, public sector entities, and privacy-conscious organizations for secure file sharing and collaboration. A successful exploitation could lead to leakage of sensitive corporate or personal data stored within the Nextcloud Android app, undermining data protection compliance such as GDPR. Although the vulnerability does not allow remote exploitation, compromised or malicious insiders, or malware on a device with the vulnerable app, could leverage this flaw to extract sensitive information. This could result in reputational damage, regulatory penalties, and loss of trust. The impact is particularly relevant for organizations with mobile-first or remote workforces relying on Nextcloud Android clients for accessing sensitive documents. However, the vulnerability does not directly affect server-side components, limiting the attack surface to end-user devices. The absence of known exploits reduces immediate risk but does not eliminate the threat, especially as attackers often target mobile endpoints to bypass perimeter defenses.

1. Immediate upgrade of all Nextcloud Android clients to version 3.21.0 or later across the organization to eliminate the vulnerability. 2. Implement mobile device management (MDM) solutions to enforce app version compliance and restrict installation of outdated or unapproved apps. 3. Conduct regular audits of mobile devices accessing corporate Nextcloud instances to ensure security posture and detect unauthorized access attempts. 4. Educate users on the risks of installing unofficial or modified versions of the Nextcloud app which may exploit this vulnerability. 5. Limit sensitive data stored locally on mobile devices by leveraging Nextcloud’s server-side encryption and access controls, reducing the impact of local data exposure. 6. Monitor for unusual file access patterns or data exfiltration attempts from mobile devices using endpoint detection and response (EDR) tools. 7. Coordinate with Nextcloud support channels for any additional patches or security advisories related to this vulnerability.