CVE-2025-27471 Overview
CVE-2025-27471 is a denial-of-service vulnerability in the Microsoft Streaming Service affecting a broad range of Windows client and server operating systems. The flaw stems from sensitive data being stored in improperly locked memory [CWE-591], which an unauthorized remote attacker can leverage to disrupt service availability over the network. Microsoft published the advisory on April 8, 2025. The vulnerability affects supported Windows 10 and Windows 11 builds, along with Windows Server versions from 2008 through 2025.
Critical Impact
A network-based attacker without authentication can trigger a denial-of-service condition in the Microsoft Streaming Service, disrupting availability on affected Windows and Windows Server systems.
Affected Products
- Microsoft Windows 10 (1507, 1607, 1809, 21H2, 22H2)
- Microsoft Windows 11 (22H2, 23H2, 24H2)
- Microsoft Windows Server (2008, 2012, 2016, 2019, 2022, 2022 23H2, 2025)
Discovery Timeline
- 2025-04-08 - CVE-2025-27471 published to NVD
- 2025-04-08 - Microsoft releases security update for CVE-2025-27471
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-27471
Vulnerability Analysis
The vulnerability resides in the Microsoft Streaming Service, a component present across the Windows kernel and user-mode media handling stack. Sensitive data is placed in memory regions that are not properly locked, creating a condition where remote input can force the service into an unavailable state. The result is a denial of service rather than data exposure, since the CIA impact is limited to availability.
The attack requires no authentication and no user interaction, but the attack complexity is high. High complexity typically indicates that an attacker must win a timing window, meet specific memory conditions, or manipulate concurrent operations to reliably trigger the fault. This aligns with the [CWE-591] classification, which covers sensitive data stored in improperly locked memory.
Root Cause
The root cause is improper memory locking around sensitive data structures used by the Streaming Service. When memory pages holding this data are not correctly locked, they can be paged out, accessed concurrently, or manipulated in ways the service does not anticipate. Attacker-controlled network input that interacts with these unlocked regions causes the service to fail, denying availability to legitimate consumers.
Attack Vector
The attack vector is the network. An attacker sends crafted traffic to a system running the Microsoft Streaming Service and does not need any prior privileges. Because the attack complexity is rated high, weaponization requires precise conditions. The EPSS score of 1.167% places CVE-2025-27471 in the 63rd percentile for exploitation likelihood, indicating moderate relative risk but no confirmed in-the-wild activity. No public proof-of-concept or exploit has been observed.
No verified proof-of-concept code is available for CVE-2025-27471.
Refer to the Microsoft Security Response Center advisory for technical
details and remediation guidance.
Detection Methods for CVE-2025-27471
Indicators of Compromise
- Unexpected termination or restart of the Microsoft Streaming Service (MSKSSRV.sys and related components) on affected hosts.
- Windows Event Log entries indicating service crashes, kernel faults, or bug checks correlated with streaming media components.
- Bursts of anomalous inbound network traffic directed at hosts running Microsoft Streaming Service functionality.
Detection Strategies
- Monitor for repeated service failures tied to the Microsoft Streaming Service and correlate against inbound network telemetry to identify remote triggering.
- Baseline normal streaming service activity and alert on deviations, especially unusual crash frequencies on Windows Server hosts.
- Track patch state across all Windows and Windows Server endpoints to identify systems still exposed to CVE-2025-27471.
Monitoring Recommendations
- Enable and forward Windows System and Application event logs to a centralized SIEM for correlation.
- Alert on Service Control Manager events tied to unexpected streaming service restarts.
- Watch for kernel-mode crash dumps referencing streaming service modules and flag them for triage.
How to Mitigate CVE-2025-27471
Immediate Actions Required
- Apply the Microsoft security update referenced in the Microsoft Security Update CVE-2025-27471 advisory to all affected Windows and Windows Server systems.
- Prioritize patching internet-exposed hosts and servers providing streaming or media services.
- Inventory affected Windows and Windows Server versions and confirm patch deployment through configuration management tooling.
Patch Information
Microsoft issued security updates addressing CVE-2025-27471 on April 8, 2025. Consult the Microsoft Security Update CVE-2025-27471 advisory for the specific KB articles that correspond to each affected Windows and Windows Server build. Apply the update through Windows Update, WSUS, or your endpoint management platform.
Workarounds
- No official workaround has been published by Microsoft. Patching is the recommended remediation.
- Restrict network access to hosts running the Microsoft Streaming Service using host-based firewall rules until updates are applied.
- Segment media and streaming servers from untrusted networks to reduce the exposed attack surface.
# Verify installed updates on a Windows host to confirm remediation
wmic qfe list brief /format:table
# PowerShell alternative to list recent hotfixes
Get-HotFix | Sort-Object -Property InstalledOn -Descending
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
