CVE-2025-9870: Razer Synapse 3 Privilege Escalation Flaw

CVE-2025-9870 Overview

CVE-2025-9870 is a local privilege escalation vulnerability in Razer Synapse 3, specifically within the RazerPhilipsHueUninstall component of the Philips HUE module installer. The flaw allows local attackers who already possess low-privileged code execution to escalate to SYSTEM by abusing a symbolic link (symlink) primitive. The installer performs file operations without properly validating link targets, enabling arbitrary file deletion. Tracked by the Zero Day Initiative as ZDI-CAN-26375, the issue is categorized under CWE-59: Improper Link Resolution Before File Access.

Critical Impact
A local, authenticated attacker can convert arbitrary file deletion into full SYSTEM-level code execution on Windows hosts running vulnerable Razer Synapse 3 installations.

Affected Products

Razer Synapse 3 (Windows configuration utility)
Razer Synapse 3 Philips HUE integration module
RazerPhilipsHueUninstall installer component

Discovery Timeline

2025-10-29 - CVE-2025-9870 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-9870

Vulnerability Analysis

The vulnerability resides in the Philips HUE module uninstaller shipped with Razer Synapse 3. The uninstaller runs with elevated privileges and performs file operations on paths that a low-privileged user can influence. Because the uninstaller does not verify whether target paths are symbolic links, junctions, or hard links before acting on them, an attacker can redirect privileged file operations to arbitrary locations. This is a classic link-following flaw on Windows, mapped to [CWE-59].

Exploitation converts a file deletion primitive into privilege escalation. Windows offers well-documented techniques for turning arbitrary file delete-as-SYSTEM into arbitrary code execution, typically by staging a Windows Installer rollback or reclaiming a deleted directory to plant a malicious DLL that a SYSTEM service later loads.

Root Cause

The root cause is improper link resolution before file access. The RazerPhilipsHueUninstall process opens or deletes files using paths under a directory writable by standard users, without impersonating the caller, without opening handles with FILE_FLAG_OPEN_REPARSE_POINT, and without validating the final resolved path. An attacker replaces a target file or subdirectory with a symlink or NTFS junction pointing to a SYSTEM-owned resource, and the privileged process follows the link.

Attack Vector

Exploitation requires local access and the ability to execute code as a standard user. The attacker plants a symbolic link within a directory used by the Philips HUE uninstaller, then triggers the uninstall workflow. The privileged installer follows the crafted link and deletes a file the attacker could not otherwise touch. The attacker then leverages a Windows arbitrary-file-delete-to-SYSTEM technique to gain code execution in the context of NT AUTHORITY\SYSTEM.

No verified public proof-of-concept code is available at this time. See the Zero Day Initiative Advisory ZDI-25-921 for additional technical context.

Detection Methods for CVE-2025-9870

Indicators of Compromise

Creation of symbolic links, junctions, or reparse points by non-administrative users under Razer Synapse or Philips HUE installer directories.
Unexpected file deletions in protected paths such as C:\Windows\System32 or C:\Program Files correlated with Razer uninstaller activity.
Child processes of RazerPhilipsHueUninstall or Razer service processes spawning cmd.exe, powershell.exe, or other interactive shells.
New or modified DLLs in SYSTEM-writable paths shortly after Razer Synapse module operations.

Detection Strategies

Monitor Windows Sysmon Event ID 11 (FileCreate) and Event ID 15 (FileCreateStreamHash) for reparse point creation by low-privileged users in Razer installation paths.
Alert on process lineage where Razer installer or service processes running as SYSTEM spawn user-controlled binaries.
Correlate high-frequency file operations on \??\ device paths and NTFS junctions with Razer Synapse activity.

Monitoring Recommendations

Enable command-line and process-creation auditing across endpoints that run Razer Synapse 3.
Baseline expected behavior of Razer service accounts and flag deviations, especially file writes outside standard Razer directories.
Forward endpoint telemetry to a centralized analytics platform for retroactive hunting across the Razer Synapse installed base.

How to Mitigate CVE-2025-9870

Immediate Actions Required

Inventory all Windows endpoints with Razer Synapse 3 installed, prioritizing developer, executive, and shared workstations.
Uninstall the Philips HUE integration module on hosts that do not require it.
Restrict local logon and interactive access on high-value systems until a fix is applied.
Enforce application control policies that block unauthorized executables from launching under SYSTEM context.

Patch Information

At the time of publication, no vendor advisory or fixed version was linked from the NVD entry for CVE-2025-9870. Refer to the Zero Day Initiative Advisory ZDI-25-921 and the official Razer support channels for updated patch availability. Apply the vendor-supplied update as soon as it is released, and validate that the RazerPhilipsHueUninstall component is replaced.

Workarounds

Remove the Philips HUE module from Razer Synapse 3 on endpoints where it is not needed.
Prevent standard users from creating symbolic links by ensuring the SeCreateSymbolicLinkPrivilege right is not granted to non-administrators.
Restrict write access to Razer installer working directories so that only administrators can stage files that the elevated uninstaller will touch.
Consider removing Razer Synapse 3 entirely from servers and production endpoints where consumer peripheral software is not required.

bash

# Verify that standard users cannot create symbolic links (run as admin, PowerShell)
secedit /export /cfg C:\secpol.cfg
Select-String -Path C:\secpol.cfg -Pattern "SeCreateSymbolicLinkPrivilege"

# Remove the Philips HUE module or uninstall Razer Synapse 3 where not required
Get-Package -Name "*Razer*" | ForEach-Object { Write-Host $_.Name }
# Uninstall via vendor uninstaller once a patched build is available