CVE-2026-56879 in Android
Summary
by MITRE • 09/15/2026
In gmc_mb_msg_handler of gmc_mba.c, there is a possible memory corruption due to a confused deputy. This could lead to local escalation of privilege with System execution privileges needed. User interaction is not needed for exploitation.
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Analysis
by VulDB Data Team • 09/15/2026
The vulnerability identified in the gmc_mb_msg_handler function within the gmc_mba.c source file represents a critical security flaw rooted in improper access control mechanisms, specifically categorized under the Confused Deputy pattern. This architectural weakness allows an attacker to manipulate system behavior by exploiting the trust relationship between different privilege levels or user contexts. In this scenario, the handler processes messages without sufficiently validating whether the requesting entity has legitimate authority to perform the specific operation requested. The core technical flaw lies in the failure of the kernel module to enforce strict identity verification before executing privileged operations based on incoming message parameters. This lack of validation enables a malicious process running at lower privilege levels to craft specially designed input that tricks the system into performing actions intended for higher-privileged entities or internal subsystems, effectively bypassing standard security boundaries.
From an operational impact perspective, this vulnerability facilitates local escalation of privileges with significant consequences for system integrity and confidentiality. Because the exploitation does not require user interaction, it can be triggered automatically by background processes or scripts once access to the vulnerable component is obtained. The attacker gains System execution privileges, which equates to complete control over the operating environment. This level of access allows for the installation of persistent backdoors, modification of critical system files, theft of sensitive data stored on the local machine, and further lateral movement within a networked infrastructure. The absence of user interaction significantly lowers the barrier to entry for attackers, making this vulnerability particularly dangerous in multi-user environments or systems exposed to untrusted inputs through automated services.
The technical classification of this issue aligns closely with CWE-269, which addresses Improper Privilege Management, and more specifically reflects aspects of CWE-841 regarding Improper Enforcement of Behavioral Workflow where the system fails to follow secure design principles for message handling. In terms of adversary tactics, this vulnerability supports techniques associated with MITRE ATT&CK ID T1068, Exploitation for Privilege Escalation, and potentially T1548 if it involves abusing access control mechanisms like Setuid or similar kernel-level privileges. The confused deputy problem here indicates a fundamental design flaw where the system acts on behalf of an entity without verifying that the entity is authorized to act in that capacity, leading to unauthorized state changes within the kernel space.
Mitigation strategies must focus on both immediate patching and long-term architectural improvements. Immediate remediation involves applying vendor-provided security patches that address the validation logic within gmc_mb_msg_handler to ensure strict identity checks are performed before processing any messages. Developers should implement rigorous input validation techniques, ensuring that all parameters passed to privileged functions are verified against expected ranges and types. Furthermore, adopting a principle of least privilege across kernel modules can reduce the attack surface by limiting the capabilities granted to individual components. Long-term solutions include integrating formal verification methods into the development lifecycle to detect confused deputy vulnerabilities early in the design phase and employing static analysis tools configured to identify improper access control patterns in C codebases. Regular security audits focusing on inter-process communication mechanisms will also help maintain robust defenses against such privilege escalation vectors.