CVE-2025-55685: Windows 10 21H2 Use After Free Vulnerability

CVE-2025-55685 Overview

CVE-2025-55685 is a use-after-free vulnerability [CWE-416] in the Windows Print Workflow User Service (PrintWorkflowUserSvc). An authenticated local attacker can trigger the flaw to elevate privileges on affected Windows client and server platforms. Microsoft published the advisory on October 14, 2025, and the issue affects a broad set of supported Windows 10, Windows 11, and Windows Server releases.

The vulnerability requires local access and low privileges, but does not require user interaction. Successful exploitation impacts confidentiality, integrity, and availability of the target host.

Critical Impact
Local privilege escalation to higher integrity in PrintWorkflowUserSvc, enabling attackers to move from standard user context toward SYSTEM-level operations on the affected host.

Affected Products

Microsoft Windows 10 (21H2, 22H2)
Microsoft Windows 11 (22H2, 23H2, 24H2, 25H2)
Microsoft Windows Server 2022, Server 2022 23H2, and Server 2025

Discovery Timeline

2025-10-14 - CVE-2025-55685 published to the National Vulnerability Database (NVD)
2025-10-14 - Microsoft released the CVE-2025-55685 security advisory
2026-06-17 - Last updated in the NVD database

Technical Details for CVE-2025-55685

Vulnerability Analysis

The flaw resides in PrintWorkflowUserSvc, a per-user service that brokers print workflow operations between applications and the Windows print subsystem. A use-after-free condition occurs when the service releases an object while another code path retains and dereferences a stale reference. Reusing that freed allocation lets an attacker influence object contents and manipulate control flow inside the service process.

Exploitation is local and requires an authenticated session on the target. The advisory notes elevated attack complexity, which typically indicates the attacker must win a race or satisfy specific timing and memory-layout conditions to reliably reclaim the freed allocation. When the conditions align, the attacker gains code execution in the service context and can escalate privileges beyond the caller's original access.

Root Cause

The root cause is improper object lifetime management inside PrintWorkflowUserSvc. Handler code continues to use a pointer to a heap object after the object has been freed, matching the classic Use After Free pattern described in [CWE-416]. Because the print workflow service handles inter-process communication, a low-privileged caller can drive the service into the vulnerable state through crafted requests.

Attack Vector

An attacker with an interactive or programmatic local session issues a sequence of calls to PrintWorkflowUserSvc designed to trigger deallocation of a tracked object while a concurrent operation still references it. The attacker then sprays or reallocates controlled data into the reclaimed memory. When the service dereferences the stale pointer, attacker-controlled data influences execution, resulting in privilege elevation within the service's security context. See the Microsoft CVE-2025-55685 Advisory for vendor guidance. No public proof-of-concept code is available at this time.

Detection Methods for CVE-2025-55685

Indicators of Compromise

Unexpected crashes, restarts, or WER (Windows Error Reporting) entries referencing PrintWorkflowUserSvc.dll or the PrintWorkflow service host.
New child processes or DLL loads originating from the PrintWorkflowUserSvc service that do not belong to Windows print infrastructure.
Standard user accounts followed by process activity running at higher integrity or SYSTEM levels shortly after print workflow interactions.

Detection Strategies

Monitor Sysmon Event ID 1 (process creation) and Event ID 7 (image loaded) for anomalous activity spawned by svchost.exe hosting PrintWorkflowUserSvc.
Review Application and System event logs for repeated service failures or exception codes such as 0xC0000005 tied to the print workflow service.
Alert on local privilege transitions where a non-administrative user session is followed by high-integrity token use without a legitimate elevation event.

Monitoring Recommendations

Baseline normal PrintWorkflowUserSvc behavior in your environment and flag deviations in call frequency, crash rate, and child process creation.
Forward endpoint telemetry to a centralized analytics platform to correlate print service anomalies with subsequent privilege changes.
Track patch state across all Windows 10, 11, and Server builds listed in the advisory to identify unpatched hosts exposed to local attackers.

How to Mitigate CVE-2025-55685

Immediate Actions Required

Apply the October 2025 Microsoft security updates addressing CVE-2025-55685 on all affected Windows 10, Windows 11, and Windows Server systems.
Prioritize patch deployment on multi-user hosts such as Remote Desktop Session Hosts, VDI pools, and shared workstations where local attackers are most likely to gain a foothold.
Audit local account membership and remove unnecessary interactive logon rights to reduce the pool of users who can reach PrintWorkflowUserSvc.

Patch Information

Microsoft has released fixes through the standard monthly security update channel. Refer to the Microsoft CVE-2025-55685 Advisory for the specific KB numbers matching each affected Windows build and install them via Windows Update, WSUS, Microsoft Update Catalog, or your patch management platform.

Workarounds

Disable the Print Workflow User Service on systems that do not require modern print workflow features, after validating application compatibility.
Restrict printer installation and print-related capabilities for standard users via Group Policy where operational requirements allow.
Enforce application allow-listing and least privilege to limit which local processes can invoke the vulnerable service surface.

bash

# Configuration example: query and disable PrintWorkflowUserSvc where permitted
sc.exe query PrintWorkflowUserSvc
sc.exe config PrintWorkflowUserSvc start= disabled
sc.exe stop PrintWorkflowUserSvc