CVE-2026-21345
📋 TL;DR
CVE-2026-21345 is an out-of-bounds read vulnerability in Substance3D Stager that could allow arbitrary code execution when a user opens a malicious file. This affects users of Substance3D Stager versions 3.1.6 and earlier. Successful exploitation requires user interaction through opening a crafted file.
💻 Affected Systems
- Adobe Substance3D Stager
📦 What is this software?
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise through remote code execution in the context of the current user, potentially leading to data theft, ransomware deployment, or lateral movement.
Likely Case
Local privilege escalation or application crash leading to denial of service, with potential for limited code execution depending on exploit sophistication.
If Mitigated
Application crash without code execution if memory protections are enabled, resulting in denial of service only.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious file) and bypassing memory protections like ASLR/DEP.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 3.1.7 or later
Vendor Advisory: https://helpx.adobe.com/security/products/substance3d_stager/apsb26-20.html
Restart Required: Yes
Instructions:
1. Open Substance3D Stager. 2. Navigate to Help > Check for Updates. 3. Install available updates. 4. Restart the application.
🔧 Temporary Workarounds
Restrict file processing
allConfigure application to only open trusted files from known sources
User awareness training
allTrain users to avoid opening untrusted Substance3D files from unknown sources
🧯 If You Can't Patch
- Implement application control to block execution of vulnerable versions
- Use email/web filtering to block suspicious Substance3D file attachments
🔍 How to Verify
Check if Vulnerable:
Check Substance3D Stager version in application settings or About dialogCheck Version:
On Windows: Check Help > About in application. On macOS: Substance3D Stager > About Substance3D StagerVerify Fix Applied:
Verify version is 3.1.7 or later after update📡 Detection & Monitoring
Log Indicators:
- Application crash logs with memory access violations
- Unexpected file processing from untrusted sources
Network Indicators:
- Downloads of Substance3D files from suspicious sources
SIEM Query:
EventID=1000 OR EventID=1001 AND ProcessName="Substance3D Stager.exe" AND ExceptionCode=0xC0000005