CVE-2025-27476: Windows 10 1809 Privilege Escalation Flaw

CVE-2025-27476 Overview

CVE-2025-27476 is a use-after-free vulnerability [CWE-416] in the Windows Digital Media component. An authorized local attacker can exploit the flaw to elevate privileges on affected systems. Microsoft published the advisory on April 8, 2025, covering supported versions of Windows 10, Windows 11, and Windows Server.

Successful exploitation grants high confidentiality, integrity, and availability impact on the target host. The attacker requires only low privileges and no user interaction to trigger the condition. No public proof-of-concept exists at this time, and the vulnerability is not listed in the CISA Known Exploited Vulnerabilities catalog.

Critical Impact
An authenticated local user can elevate privileges to SYSTEM by triggering use-after-free conditions in the Windows Digital Media subsystem.

Affected Products

Microsoft Windows 10 (1809, 21H2, 22H2)
Microsoft Windows 11 (22H2, 23H2, 24H2)
Microsoft Windows Server 2019, Server 2022 23H2, and Server 2025

Discovery Timeline

2025-04-08 - CVE-2025-27476 published to NVD
2025-04-08 - Microsoft releases security patch via Patch Tuesday
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-27476

Vulnerability Analysis

The vulnerability resides in the Windows Digital Media subsystem, which handles multimedia processing for the operating system. A use-after-free condition occurs when the component references memory that has already been freed. An attacker with local access and low privileges can manipulate object lifetimes to trigger the flaw.

Exploitation results in execution within the context of a higher-privileged process. This typically enables elevation from a standard user account to SYSTEM. The local attack vector limits remote exploitation but makes this vulnerability valuable in post-compromise scenarios such as ransomware staging.

The current EPSS probability sits at 0.601%, reflecting limited observed exploitation activity to date. However, use-after-free flaws in kernel-adjacent Windows components are historically weaponized after patch analysis.

Root Cause

The root cause is improper memory management in Digital Media object handling [CWE-416]. Code paths release a memory allocation but retain and later dereference a pointer to that region. When an attacker controls the reallocation, the dangling pointer references attacker-supplied data.

Attack Vector

The attack requires local access with authenticated low privileges. An attacker executes crafted code that interacts with Digital Media interfaces to invoke the vulnerable code path. Race conditions or specifically ordered API calls are typically required to reliably trigger the free-then-use sequence. Refer to the Microsoft Security Update CVE-2025-27476 advisory for vendor-specific technical context.

Detection Methods for CVE-2025-27476

Indicators of Compromise

Unexpected child processes spawned from Digital Media related services or media handler processes running as SYSTEM.
Application crashes referencing Digital Media modules in the Windows Event Log, especially prior to privilege escalation attempts.
Loading of unsigned or unusual DLLs into processes that interact with the Digital Media subsystem.

Detection Strategies

Monitor for local processes that transition from a standard user token to a SYSTEM or elevated token without a legitimate elevation prompt.
Track anomalous access patterns to Digital Media APIs from non-media applications or scripting hosts.
Correlate crash telemetry with subsequent process creation events to identify exploitation attempts against use-after-free primitives.

Monitoring Recommendations

Ingest Windows Security, Sysmon, and WER (Windows Error Reporting) logs into a centralized data lake for correlation.
Alert on rapid succession of media-handling process crashes followed by privileged process creation on the same host.
Baseline normal Digital Media component behavior per host role to surface deviations tied to exploitation.

How to Mitigate CVE-2025-27476

Immediate Actions Required

Apply the April 2025 Microsoft security update addressing CVE-2025-27476 across all affected Windows client and Server SKUs.
Prioritize patching multi-user systems, jump servers, and endpoints accessible by low-privileged users.
Audit local account membership and remove unnecessary interactive logon rights where feasible.

Patch Information

Microsoft released fixes for this vulnerability as part of the April 8, 2025 security update cycle. Detailed KB numbers per Windows build are available in the Microsoft Security Update CVE-2025-27476 guidance. Administrators should validate patch deployment status using WSUS, Intune, or SCCM reporting.

Workarounds

No official workarounds are documented by Microsoft; applying the security update is the required remediation path.
Restrict local logon rights and enforce application allowlisting to reduce the population of users able to execute exploit code.
Use attack surface reduction rules and least-privilege configurations to limit lateral movement following successful elevation.

bash

# Verify patch installation on Windows hosts
Get-HotFix | Where-Object { $_.InstalledOn -ge (Get-Date '2025-04-08') } | Sort-Object InstalledOn

# Confirm current OS build to match against Microsoft's KB matrix
[System.Environment]::OSVersion.Version
(Get-ItemProperty 'HKLM:\SOFTWARE\Microsoft\Windows NT\CurrentVersion').DisplayVersion