CVE-2025-54894: Windows 10 1507 Privilege Escalation Flaw

CVE-2025-54894 Overview

CVE-2025-54894 is an elevation of privilege vulnerability in the Windows Local Security Authority Subsystem Service (LSASS). The flaw stems from a heap-based buffer overflow condition [CWE-122] within LSASS, a core component that enforces the security policy on Windows systems. A locally authenticated attacker can exploit the weakness to elevate privileges on affected Windows client and server operating systems. Microsoft assigned the vulnerability a CVSS 3.1 base score of 7.8 and rated it HIGH severity. The vulnerability affects a broad range of supported Windows releases, including Windows 10, Windows 11, and Windows Server editions from 2008 through 2025.

Critical Impact

Successful exploitation grants attackers full compromise of the affected host, with high impact to confidentiality, integrity, and availability of the target system.

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, and 2025

Discovery Timeline

• 2025-09-09 - CVE-2025-54894 published to NVD
• 2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-54894

Vulnerability Analysis

The vulnerability resides in the Local Security Authority Subsystem Service (lsass.exe), the Windows process responsible for enforcing local security policy, handling user logons, verifying credentials, and managing security tokens. A heap-based buffer overflow [CWE-122] in LSASS allows a low-privileged local user to corrupt heap memory during service processing. Because LSASS runs as NT AUTHORITY\SYSTEM, controlled heap corruption within its address space can be leveraged to gain SYSTEM-level privileges. The attack does not require user interaction and can be executed by any authenticated user with local access to an affected host.

Root Cause

The underlying defect is a heap-based buffer overflow within a code path processed by LSASS. Insufficient bounds checking on attacker-influenced data structures allows a write past an allocated heap buffer, corrupting adjacent heap metadata or object pointers. Because LSASS handles authentication material and security tokens, corrupting its heap can subvert access decisions or redirect execution.

Attack Vector

Exploitation requires local access and low-privileged authenticated credentials. An attacker executes a specially crafted program that interacts with LSASS through an exposed local interface, triggering the vulnerable code path. Successful exploitation yields code execution in the LSASS process context, resulting in full privilege escalation. This class of vulnerability is often chained with initial-access techniques such as phishing, malicious documents, or compromised standard user accounts. See the Microsoft CVE-2025-54894 Advisory for vendor-supplied technical details.

Detection Methods for CVE-2025-54894

Indicators of Compromise

• Unexpected child processes spawned by lsass.exe, such as cmd.exe, powershell.exe, or unknown binaries running as SYSTEM.
• Crash events or Windows Error Reporting entries referencing lsass.exe heap corruption, access violations, or unexpected termination.
• New or unusual local RPC or ALPC connections to LSASS originating from low-privileged user sessions.
• Creation of scheduled tasks, services, or accounts immediately following anomalous LSASS activity.

Detection Strategies

• Monitor for process integrity level transitions where a Medium or Low integrity process is followed by SYSTEM-level activity on the same host.
• Alert on any handle open to lsass.exe with write or process-manipulation access rights from non-security tooling.
• Correlate Windows Event ID 4672 (special privileges assigned) with recently created processes from standard user accounts.
• Use behavioral analytics to detect memory-write anomalies and token manipulation targeting LSASS.

Monitoring Recommendations

• Enable and forward Sysmon events (IDs 1, 8, 10, 25) with LSASS-focused rules to a centralized SIEM or data lake.
• Ensure LSA Protection (RunAsPPL) and Credential Guard telemetry are collected and reviewed regularly.
• Baseline normal LSASS access patterns per host role and alert on deviations, including from allow-listed EDR tools.

How to Mitigate CVE-2025-54894

Immediate Actions Required

• Apply the Microsoft security update for CVE-2025-54894 to all affected Windows client and server systems as a priority.
• Inventory endpoints and servers against the affected version list and prioritize patching of domain controllers and privileged-tier hosts.
• Restrict local logon rights and remove unnecessary interactive access for standard users on sensitive systems.
• Enable LSA Protection (RunAsPPL) and Credential Guard where supported to raise the exploitation bar.

Patch Information

Microsoft published fixes as part of its September 2025 security update cycle. Refer to the Microsoft CVE-2025-54894 Advisory for the specific KB articles, cumulative updates, and product build numbers applicable to each affected Windows release. Deploy the vendor updates through Windows Update, WSUS, Microsoft Update Catalog, or your enterprise patch management tooling.

Workarounds

• Microsoft has not published a supported workaround; installing the security update is the required remediation.
• Reduce exposure by limiting the number of accounts with interactive local logon rights on high-value hosts until patches are deployed.
• Enforce application allow-listing (for example, Windows Defender Application Control) to block untrusted binaries that could stage exploitation.

# Verify LSA Protection is enabled (PowerShell, run as Administrator)
Get-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Lsa' -Name RunAsPPL

# Enable LSA Protection (requires reboot)
New-ItemProperty -Path 'HKLM:\SYSTEM\CurrentControlSet\Control\Lsa' `
  -Name 'RunAsPPL' -Value 1 -PropertyType DWord -Force