CVE-2025-49148 Overview
CVE-2025-49148 is a DLL search order hijacking vulnerability in ClipShare Server for Windows, a lightweight cross-platform clipboard sharing tool. Versions prior to 3.8.5 load system libraries such as CRYPTBASE.dll and WindowsCodecs.dll from the application's own directory before falling back to the Windows system path. A local, non-privileged user with write access to the directory containing clip_share.exe can drop a malicious DLL that executes in the server's process context. When the server runs under an Administrator account, exploitation yields reliable local privilege escalation [CWE-427]. The issue is fixed in ClipShare 3.8.5.
Critical Impact
Local attackers with write access to the ClipShare installation directory can achieve arbitrary code execution and, when the binary is launched by an elevated user, full local privilege escalation.
Affected Products
- ClipShare Server for Windows versions prior to 3.8.5
- clip_share.exe binary and its installation directory
- Windows deployments where the ClipShare directory is user-writable
Discovery Timeline
- 2025-06-11 - CVE-2025-49148 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2025-49148
Vulnerability Analysis
ClipShare Server for Windows follows the default Windows DLL search order when loading dependencies at runtime. Under this order, the directory containing the executable is searched before protected system paths such as C:\Windows\System32. The server references common system libraries including CRYPTBASE.dll and WindowsCodecs.dll without specifying a fully qualified path or restricting the search using SetDefaultDllDirectories or LoadLibraryEx flags.
An attacker who can write to the ClipShare installation folder places a malicious DLL matching one of these library names. When clip_share.exe starts, the loader resolves the attacker-controlled DLL first and executes its DllMain in the process context. If an Administrator later launches the server, the injected code runs with elevated privileges, converting a local user foothold into full system compromise.
Root Cause
The root cause is uncontrolled search path element handling [CWE-427]. ClipShare does not enforce a safe DLL loading policy, so the executable's directory is trusted for locating imports that should originate from the operating system.
Attack Vector
Exploitation requires local access and write permission to the folder hosting clip_share.exe. The attacker drops a crafted DLL named after a dynamically loaded system library and waits for the server to launch. No user interaction beyond starting the server is required, and no network access is needed. See the GitHub Security Advisory GHSA-rc47-h83g-2r8j for the maintainer's technical write-up.
Detection Methods for CVE-2025-49148
Indicators of Compromise
- Presence of CRYPTBASE.dll, WindowsCodecs.dll, or other system-named DLLs inside the ClipShare installation directory
- Unsigned or unexpectedly signed DLL modules loaded by clip_share.exe
- Recent file creation events in the ClipShare directory authored by non-administrative accounts
Detection Strategies
- Enumerate loaded modules for clip_share.exe and validate that system DLLs resolve to C:\Windows\System32 rather than the application folder
- Alert on process image loads where the DLL path parent directory matches the ClipShare install path
- Correlate module load telemetry with recent write events to the application directory by non-privileged users
Monitoring Recommendations
- Monitor Sysmon Event ID 7 (Image Loaded) and Event ID 11 (FileCreate) scoped to the ClipShare directory
- Track EDR module-load telemetry for signature anomalies on CRYPTBASE.dll and WindowsCodecs.dll
- Audit NTFS permissions on the ClipShare install path and flag write access granted to standard users
How to Mitigate CVE-2025-49148
Immediate Actions Required
- Upgrade ClipShare Server for Windows to version 3.8.5 or later
- Relocate clip_share.exe into a directory that only administrators can write to, such as C:\Program Files\ClipShare
- Remove any unexpected DLL files present in the current ClipShare directory and investigate their origin
Patch Information
The vendor released ClipShare 3.8.5, which addresses the insecure DLL loading behavior. Details and remediation guidance are published in the GitHub Security Advisory GHSA-rc47-h83g-2r8j.
Workarounds
- Restrict NTFS write permissions on the folder containing clip_share.exe to administrators only
- Do not launch ClipShare Server from user-writable locations such as Downloads, Desktop, or per-user AppData
- Avoid running ClipShare under Administrator or other elevated accounts until the patch is applied
# Configuration example: restrict write access on the ClipShare directory
icacls "C:\Program Files\ClipShare" /inheritance:r
icacls "C:\Program Files\ClipShare" /grant:r "Administrators:(OI)(CI)F" "SYSTEM:(OI)(CI)F" "Users:(OI)(CI)RX"
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
