CVE-2000-0849 in Windows Media Services
Summary
by MITRE
Race condition in Microsoft Windows Media server allows remote attackers to cause a denial of service in the Windows Media Unicast Service via a malformed request, aka the "Unicast Service Race Condition" vulnerability.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 10/12/2025
The CVE-2000-0849 vulnerability represents a critical race condition flaw within Microsoft Windows Media Server that specifically targets the Windows Media Unicast Service. This vulnerability emerges from improper synchronization mechanisms in the service handling code, creating a window of opportunity for malicious actors to exploit temporal inconsistencies in request processing. The flaw manifests when the service receives malformed requests that trigger concurrent execution paths without adequate mutual exclusion controls, leading to unpredictable system behavior and eventual service termination.
The technical implementation of this race condition occurs at the kernel level within the Windows Media Unicast Service component, where multiple threads attempt to access shared resources simultaneously without proper locking mechanisms. When a specially crafted malformed request is sent to the service, it can cause the system to enter an inconsistent state where memory structures become corrupted or invalid pointers are dereferenced. This particular vulnerability falls under CWE-362, which specifically addresses race conditions in software implementations, and aligns with ATT&CK technique T1499.004 for network denial of service attacks targeting media services.
The operational impact of this vulnerability extends beyond simple service disruption, as it can be exploited by remote attackers without authentication requirements, making it particularly dangerous in networked environments. The denial of service condition affects the availability of media streaming services, potentially impacting organizations that rely on Windows Media Server for content delivery. Attackers can repeatedly send malformed requests to exhaust system resources or trigger the race condition repeatedly, causing sustained service unavailability that can last until the service is manually restarted or the system is rebooted.
Mitigation strategies for this vulnerability require immediate patch application from Microsoft, as the flaw existed in multiple versions of Windows Media Server and could not be effectively addressed through configuration changes alone. Organizations should implement network segmentation to limit access to media streaming services and monitor for unusual traffic patterns that might indicate exploitation attempts. Additionally, deploying intrusion detection systems capable of identifying malformed requests targeting Windows Media services can provide early warning of potential attacks. The vulnerability demonstrates the importance of proper thread synchronization in server applications and highlights how seemingly minor implementation flaws can result in significant availability impacts, particularly in enterprise media delivery environments where continuous service availability is critical for business operations.