CVE-2026-56915 in Android
Summary
by MITRE • 09/15/2026
In bigo_worker_thread of bigo.c, there is a possible escalation of privilege due to a race condition. 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 within the bigo_worker_thread function in bigo.c represents a critical security flaw rooted in improper synchronization mechanisms, specifically manifesting as a time-of-check-to-time-of-use race condition. This type of defect occurs when multiple threads or processes access shared data concurrently without adequate locking or atomic operations, allowing an attacker to manipulate the state of the system between the moment a check is performed and the action based on that check is executed. In this specific context, the flaw resides in how privilege levels are validated and applied during worker thread initialization or execution. The absence of robust synchronization primitives enables a malicious actor to exploit the timing window where elevated privileges might be granted before proper authorization checks can prevent unauthorized access. This scenario aligns with CWE-362, which classifies concurrent execution using shared resources with improper synchronization as a distinct category of software errors leading to security vulnerabilities.
From an operational perspective, this race condition facilitates local privilege escalation, allowing a low-privileged user or process to gain higher-level permissions on the affected system. The description notes that System execution privileges are required for successful exploitation, indicating that once the race is won, the attacker achieves code execution with the highest level of authority available within the operating environment. This significantly expands the attack surface because it does not require any form of user interaction or social engineering to trigger. An attacker can potentially automate the exploitation process by repeatedly invoking the vulnerable function in a tight loop, increasing the probability of hitting the race window during which the system state is inconsistent and susceptible to manipulation. The lack of required user interaction makes this vulnerability particularly dangerous as it can be exploited remotely if the service exposing bigo_worker_thread is accessible over a network or locally by any authenticated user with access to the application interface.
The implications of such a flaw extend beyond simple privilege escalation, potentially leading to full system compromise. With System-level execution privileges, an attacker could install malware, exfiltrate sensitive data, modify security configurations, and establish persistent backdoors that are difficult to detect and remove. This aligns with several tactics within the MITRE ATT&CK framework, particularly those related to Privilege Escalation such as T1068 Exploitation for Privilege Escalation or T1059 Command and Scripting Interpreter if subsequent actions involve executing arbitrary commands. The ability to escalate privileges without user interaction further complicates defense-in-depth strategies, as traditional perimeter defenses may not detect the internal exploitation attempt until significant damage has been done.
Mitigation of this vulnerability requires a multi-faceted approach focusing on code hardening and system configuration. Developers must implement strict synchronization mechanisms such as mutexes, semaphores, or atomic operations to ensure that privilege checks and subsequent actions are performed atomically within bigo_worker_thread. Code reviews should specifically target race conditions in concurrent programming contexts, ensuring that shared resources are protected against simultaneous access from multiple threads. Additionally, applying the principle of least privilege is crucial; if possible, worker threads should operate with minimal necessary permissions rather than seeking elevated privileges by default. System administrators can also mitigate risk by restricting user access to the application or service hosting bigo.c until a patch is applied, and by monitoring for unusual patterns of process creation or permission changes that might indicate an exploitation attempt. Regular updates and patches provided by the vendor are essential to address these underlying code defects permanently.