CVE-2026-42900 in Windows
Summary
by MITRE • 07/14/2026
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows App Store allows an unauthorized attacker to elevate privileges over a network.
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Analysis
by VulDB Data Team • 07/14/2026
A race condition vulnerability in the Windows App Store represents a critical concurrency flaw that enables unauthorized attackers to escalate privileges remotely. This vulnerability stems from improper synchronization mechanisms when multiple processes or threads access shared resources simultaneously, creating temporal windows where system state can be manipulated. The flaw specifically manifests within the Windows App Store application's handling of concurrent operations, where insufficient locking mechanisms allow competing execution paths to interfere with each other during resource modification phases.
The technical implementation of this race condition occurs when the App Store service processes multiple simultaneous requests or operations that share common system resources such as temporary files, registry entries, or memory segments. When these shared resources are accessed without proper mutual exclusion controls, an attacker can time their malicious actions to exploit the temporal gap between resource state checks and actual modifications. This creates opportunities for privilege escalation attacks where an unauthenticated network user can manipulate system components to gain elevated privileges.
From an operational perspective, this vulnerability represents a severe threat vector since it requires no local access or authentication credentials to exploit. The remote attack surface allows adversaries to leverage network-based exploitation techniques, making the vulnerability particularly dangerous in enterprise environments where App Store services may be accessible across network boundaries. The privilege escalation capability means that successful exploitation could result in full system compromise, enabling attackers to execute arbitrary code with administrative privileges.
The underlying cause of this vulnerability aligns with common weakness patterns identified in CWE-362, which catalogs race conditions as a fundamental concurrency flaw. This weakness category specifically addresses situations where two or more threads or processes access shared data concurrently without proper synchronization, leading to unpredictable behavior and potential security exploits. The ATT&CK framework categorizes this type of vulnerability under privilege escalation techniques where adversaries leverage system-level flaws to gain elevated permissions.
Mitigation strategies should focus on implementing proper synchronization mechanisms throughout the Windows App Store codebase, including mutex locks, semaphores, or other concurrency control primitives to prevent simultaneous access to shared resources. System administrators should ensure timely patch deployment and consider network segmentation to limit access to App Store services. Additionally, implementing strict access controls and monitoring for anomalous concurrent operations can help detect potential exploitation attempts. The vulnerability highlights the critical importance of thorough concurrency testing in security-sensitive applications and adherence to secure coding practices that prevent race condition scenarios through proper resource management protocols.