CVE-2026-56649
Summary
by MITRE • 07/14/2026
Concurrent execution using shared resource with improper synchronization ('race condition') in Windows Network File System allows an unauthorized attacker to execute code over a network.
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Analysis
by VulDB Data Team • 07/14/2026
A critical race condition vulnerability exists within the Windows Network File System implementation that enables unauthorized remote code execution through improper synchronization of shared resources during concurrent operations. This vulnerability stems from insufficient coordination mechanisms when multiple processes or threads attempt to access the same network file system resources simultaneously, creating temporal windows where malicious actors can exploit the inconsistent state of shared data structures.
The technical flaw manifests when the network file system fails to properly serialize access to critical resources during concurrent read and write operations, allowing attackers to manipulate the timing of resource access to trigger unintended behavior. This race condition occurs at the kernel level within the file system driver components that handle network file operations, where multiple threads or processes can interfere with each other's execution paths when accessing shared memory regions or file handles without adequate locking mechanisms.
From an operational perspective this vulnerability presents a severe threat vector as it allows remote attackers to execute arbitrary code on affected systems without requiring local access privileges. The attack typically involves carefully timed network requests that exploit the race condition window to inject malicious code into system memory, potentially leading to full system compromise and persistence within the network environment. This capability makes the vulnerability particularly dangerous in enterprise environments where network file sharing is prevalent.
The vulnerability aligns with CWE-362, which specifically addresses race conditions in concurrent programming scenarios where improper synchronization leads to security flaws. Additionally this weakness maps to multiple ATT&CK techniques including T1059 for command and control execution and T1078 for valid accounts usage, as attackers may leverage compromised file system access to establish persistent backdoors or escalate privileges within the network infrastructure.
Mitigation strategies should focus on implementing proper synchronization mechanisms such as mutex locks, semaphores, or atomic operations when accessing shared resources in the network file system drivers. System administrators should apply Microsoft security updates promptly, implement network segmentation to limit exposure of critical file servers, and monitor for unusual concurrent access patterns that may indicate exploitation attempts. Organizations should also consider disabling unnecessary network file sharing services and implementing strict access controls through proper authentication and authorization mechanisms to reduce the attack surface available to potential adversaries exploiting this race condition vulnerability.