CVE-2025-55335: Windows 10 1507 Privilege Escalation Flaw

CVE-2025-55335 Overview

CVE-2025-55335 is a use-after-free vulnerability in the Windows NTFS file system driver. An authenticated local attacker can trigger the flaw to elevate privileges on affected systems. Microsoft published the advisory on October 14, 2025, and the issue affects a broad range of Windows client and server versions from Windows 10 through Windows Server 2025. The vulnerability is classified under [CWE-416] (Use After Free) and [CWE-362] (Concurrent Execution using Shared Resource with Improper Synchronization), indicating a race condition contributes to the memory corruption.

Critical Impact
Successful exploitation lets a low-privileged local user gain SYSTEM-level privileges on the Windows host, resulting in full compromise of confidentiality, integrity, and availability.

Affected Products

Microsoft Windows 10 (1507, 1607, 1809, 21H2, 22H2)
Microsoft Windows 11 (22H2, 23H2, 24H2, 25H2)
Microsoft Windows Server 2008, 2012, 2016, 2019, 2022, 2022 23H2, and 2025

Discovery Timeline

2025-10-14 - CVE-2025-55335 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-55335

Vulnerability Analysis

The defect resides in the NTFS driver, which manages on-disk metadata for the primary Windows file system. NTFS operations run in kernel mode, so memory corruption within the driver translates directly to kernel-level compromise. Because both [CWE-416] and [CWE-362] are assigned, the flaw involves a race between concurrent NTFS operations that leaves a freed object accessible to another code path. When the stale pointer is dereferenced, an attacker who has arranged the freed allocation can steer kernel execution or corrupt kernel objects. The result is arbitrary code execution in the context of the NT AUTHORITY\SYSTEM account.

Root Cause

The root cause is improper synchronization around the lifetime of an NTFS object. One thread frees the underlying allocation while another thread still holds and later dereferences a pointer to it. Without adequate locking or reference counting, the driver reuses the freed memory before the second thread completes its access, producing the use-after-free condition.

Attack Vector

Exploitation requires local access and low privileges. The attacker must win a race window, which raises attack complexity, but no user interaction is required. Typical exploitation involves issuing rapid, concurrent NTFS operations, such as file, stream, or attribute manipulations, from a low-privileged process to trigger the race. The attacker then reallocates the freed slot with attacker-controlled data to hijack kernel execution flow.

No public proof-of-concept exploit or exploitation-in-the-wild activity has been reported for CVE-2025-55335 at the time of publication. See the Microsoft Security Update Guide CVE-2025-55335 for vendor technical details.

Detection Methods for CVE-2025-55335

Indicators of Compromise

Unexpected ntfs.sys bugchecks or KERNEL_MODE_HEAP_CORRUPTION / DRIVER_VERIFIER_DETECTED_VIOLATION events on hosts running unpatched builds.
New processes spawned as NT AUTHORITY\SYSTEM with a parent process that runs under a standard user token.
Local user accounts creating services, scheduled tasks, or drivers immediately after high-volume NTFS I/O activity.

Detection Strategies

Alert on token elevation anomalies where a low-integrity process suddenly gains SYSTEM privileges without a legitimate elevation path.
Correlate kernel crash telemetry (WER, Minidump) referencing NTFS routines with subsequent privilege changes on the same host.
Hunt for tight loops of concurrent file, alternate data stream, or reparse point operations executed from unprivileged binaries in user-writable directories.

Monitoring Recommendations

Ingest Windows System, Security (event IDs 4672, 4688), and kernel crash logs into a centralized SIEM for correlation across hosts.
Track patch state for the October 2025 Windows cumulative updates and flag endpoints missing the fix for CVE-2025-55335.
Monitor endpoint protection telemetry for unsigned or untrusted binaries performing repeated NTFS metadata operations shortly before privilege changes.

How to Mitigate CVE-2025-55335

Immediate Actions Required

Apply the October 2025 Microsoft security updates that address CVE-2025-55335 across all Windows client and server builds listed in the advisory.
Prioritize patching multi-user systems, terminal servers, jump hosts, and developer workstations where untrusted local code is most likely to run.
Restrict local logon rights and remove unnecessary interactive accounts to reduce the population of users who can trigger the flaw.

Patch Information

Microsoft released fixes as part of its scheduled security update cycle. Consult the Microsoft Security Update Guide CVE-2025-55335 for the specific KB numbers per Windows version and install them through Windows Update, WSUS, Microsoft Update Catalog, or your enterprise patch management tooling.

Workarounds

No official vendor workaround is documented; applying the security update is the supported remediation path.
Enforce application control (Windows Defender Application Control, AppLocker) to block unapproved binaries from executing on unpatched hosts.
Enable attack surface reduction and least-privilege policies so standard users cannot introduce arbitrary code that would trigger the NTFS race.

bash

# Verify installed updates on a Windows host and confirm the KB addressing
# CVE-2025-55335 is present (replace KB number with the value from the MSRC advisory).
wmic qfe list brief /format:table
Get-HotFix | Sort-Object -Property InstalledOn -Descending | Select-Object -First 20