CVE-2026-107051 in AndFHEM
Summary
by MITRE • 10/29/2026
Insecure permissions in klassm AndFHEM v2.4.1 (versionCode 241, the verified build) allows unauthorized attackers to arbitrarily manipulate another user's FHEM home-automation control configurations.
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Analysis
by VulDB Data Team • 10/29/2026
The vulnerability identified in klassm and AndFHEM version 2.4.1 represents a critical failure in access control mechanisms within mobile-based home automation applications. This flaw stems from insecure file permissions that allow unauthorized actors to read, modify, or delete sensitive configuration data belonging to other users on the same device. In the context of Android application development, this typically manifests as an improper assignment of file modes where private application data is stored with world-readable or world-writable attributes rather than being restricted to the specific user ID and group ID associated with the app instance. This misconfiguration violates fundamental security principles regarding data isolation and confidentiality, creating a direct pathway for local privilege escalation and unauthorized state manipulation within the home automation ecosystem.
From a technical perspective, this issue aligns closely with CWE-732: Incorrect Permission Assignment for Critical Resource. The application fails to enforce strict access controls on its internal storage directories or specific configuration files where FHEM settings are persisted. When an attacker gains local execution privileges on the device, potentially through another malicious app or a compromised user session, they can bypass standard Android sandboxing mechanisms by directly accessing these improperly secured files. This allows the adversary to inject arbitrary commands into the home automation system's control logic, effectively taking over the management of connected smart devices without authentication. The vulnerability is particularly severe because it does not require network exposure; it relies solely on local access, which can be achieved through various vectors including physical device theft, social engineering leading to app installation by a malicious actor, or exploitation of other lower-severity vulnerabilities that grant file system read/write capabilities.
The operational impact of this vulnerability extends beyond simple data leakage to include significant risks to physical security and privacy. Since AndFHEM serves as an interface for controlling home automation systems such as lighting, HVAC, locks, and alarms, the ability to manipulate configurations remotely or locally can lead to dangerous real-world consequences. An attacker could disable security sensors, unlock smart doors, trigger false alarms, or disrupt critical infrastructure controlled by the system. Furthermore, because these applications often store credentials or session tokens alongside configuration data, compromising the permissions may also expose authentication material, facilitating further attacks against remote FHEM servers if they are accessible from the mobile device. This creates a chain of compromise where local file access translates into broader network and physical security breaches.
This vulnerability is also relevant to MITRE ATT&CK framework techniques related to Collection and Execution on Mobile Platforms. Specifically, it relates to T1560.002: Archive Collected Data via Local File Manipulation and potentially T1059.007: Command and Scripting Interpreter: Android Shell if the manipulated configurations allow for script execution within the FHEM environment. The lack of proper permission enforcement undermines the integrity of the application's state, allowing an attacker to persist their influence by modifying startup scripts or daemon settings that control how home automation rules are applied. This persistence mechanism ensures that even after a reboot or app restart, the malicious configurations remain active, maintaining unauthorized control over the smart home environment.
Mitigation strategies must focus on enforcing strict file system permissions and implementing robust input validation for configuration changes. Developers should ensure that all private data files created by the application use MODE_PRIVATE flags in Android APIs to restrict access exclusively to the calling app's user ID. Additionally, implementing integrity checks such as cryptographic hashing of critical configuration files can detect unauthorized modifications before they are applied. For users, it is advisable to keep applications updated to versions where this permission issue has been resolved and to avoid installing apps from untrusted sources that may exploit similar weaknesses in other home automation tools. Security audits should routinely verify file permissions across all application storage directories to prevent recurrence of such insecure configuration errors.