CVE-2025-9871: Razer Synapse 3 Privilege Escalation Flaw

CVE-2025-9871 Overview

CVE-2025-9871 is a local privilege escalation vulnerability in Razer Synapse 3, specifically within the Razer Chroma SDK installer component. The flaw stems from improper handling of symbolic links [CWE-59], allowing an authenticated local attacker to abuse the installer to delete arbitrary files on the system. Successful exploitation results in code execution in the context of NT AUTHORITY\SYSTEM. The issue was reported through the Trend Micro Zero Day Initiative as ZDI-CAN-26373 and published as ZDI-25-920.

Critical Impact
A low-privileged local user can escalate to SYSTEM by exploiting a link-following flaw in the Chroma SDK installer, leading to full compromise of the affected Windows host.

Affected Products

Razer Synapse 3
Razer Chroma SDK (installer component bundled with Synapse 3)
Windows endpoints running vulnerable Razer Synapse installations

Discovery Timeline

2025-10-29 - CVE-2025-9871 published to the National Vulnerability Database
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-9871

Vulnerability Analysis

The vulnerability is a link-following weakness [CWE-59] in the Razer Chroma SDK installer that ships with Razer Synapse 3. The installer performs file operations on paths that a low-privileged user can influence. Because the installer runs with elevated privileges, an attacker who plants a symbolic link at a targeted path can redirect a privileged file deletion to a file the attacker would not otherwise be able to remove.

Arbitrary file deletion as SYSTEM is a well-established primitive for local privilege escalation on Windows. Attackers can chain the delete to overwrite system state, replace trusted binaries, or hijack DLL search order to execute arbitrary code as SYSTEM. Local access and the ability to run low-privileged code are required, but no user interaction is needed after the exploit is triggered.

Root Cause

The root cause is insufficient validation of file system objects before performing privileged operations. The installer follows symbolic links or junctions instead of verifying that the target path is not attacker-controlled. This mirrors a common pattern in Windows installers that operate on directories writable by standard users, such as locations under C:\ProgramData or per-user temporary paths.

Attack Vector

Exploitation requires local access and the ability to execute low-privileged code. The attacker plants a symbolic link or NTFS junction pointing from a path the installer touches to a protected file the attacker wants to delete. When the installer runs with elevated privileges, it follows the link and deletes the target. The attacker then leverages the deletion primitive to gain arbitrary code execution as SYSTEM. No verified public proof-of-concept code is available; see the Zero Day Initiative Advisory ZDI-25-920 for the vendor-coordinated disclosure details.

Detection Methods for CVE-2025-9871

Indicators of Compromise

Creation of NTFS junctions or symbolic links under directories used by the Razer Chroma SDK installer, particularly by non-administrative user contexts.
Unexpected deletion of files in protected locations such as C:\Windows\System32 or C:\Program Files shortly after a Razer installer or update process runs.
New or modified binaries in system directories following execution of Razer Synapse or Chroma SDK installer processes.

Detection Strategies

Monitor for CreateSymbolicLink and reparse point creation events (Sysmon Event ID 11 with reparse indicators, or EDR file system telemetry) originating from low-privileged users targeting Razer installer paths.
Correlate installer process execution with subsequent file deletion or overwrite operations on SYSTEM-owned files.
Alert on child processes of Razer installer components that spawn command interpreters such as cmd.exe or powershell.exe running as SYSTEM.

Monitoring Recommendations

Enable file integrity monitoring on system directories and Razer installation paths to detect unauthorized deletions or replacements.
Ingest Windows Security, Sysmon, and EDR telemetry into a centralized data lake for cross-event correlation of link-following exploitation patterns.
Baseline expected behavior for Razer Synapse installer and update processes, then alert on deviations such as arbitrary file writes outside install directories.

How to Mitigate CVE-2025-9871

Immediate Actions Required

Inventory all Windows endpoints running Razer Synapse 3 and the Razer Chroma SDK, prioritizing shared and privileged workstations.
Apply the vendor-supplied update as soon as Razer publishes a fixed release referenced in ZDI-25-920.
Restrict interactive local logon on sensitive systems to limit which users can stage a symbolic link exploit.

Patch Information

At the time of publication, refer to the Zero Day Initiative Advisory ZDI-25-920 for coordinated disclosure status and to the Razer support site for the fixed Synapse 3 and Chroma SDK build numbers. Deploy the vendor patch through standard software distribution channels once released and verify installed versions post-deployment.

Workarounds

Uninstall Razer Synapse 3 and the Chroma SDK from systems that do not require Razer peripheral management until a patched version is deployed.
Remove or restrict write permissions on directories used by the Chroma SDK installer so standard users cannot create reparse points in those paths.
Disable the SeCreateSymbolicLinkPrivilege for non-administrative users via Group Policy where operational requirements permit.

bash

# Group Policy path to restrict symbolic link creation for standard users:
# Computer Configuration > Windows Settings > Security Settings >
#   Local Policies > User Rights Assignment > "Create symbolic links"
#
# Verify current holders of the privilege:
whoami /priv | findstr SeCreateSymbolicLinkPrivilege

# Check installed Razer Synapse version on an endpoint:
Get-ItemProperty "HKLM:\Software\Microsoft\Windows\CurrentVersion\Uninstall\*" |
  Where-Object { $_.DisplayName -like "*Razer*" } |
  Select-Object DisplayName, DisplayVersion, Publisher