CVE-2025-21156
📋 TL;DR
An integer underflow vulnerability in Adobe InCopy allows arbitrary code execution when a user opens a malicious file. This affects users of InCopy versions 20.0, 19.5.1 and earlier. Successful exploitation requires user interaction through opening a specially crafted file.
💻 Affected Systems
- Adobe InCopy
📦 What is this software?
Incopy by Adobe
Incopy by Adobe
⚠️ Risk & Real-World Impact
Worst Case
Full system compromise with attacker gaining the same privileges as the current user, potentially leading to data theft, ransomware deployment, or persistent backdoor installation.
Likely Case
Local privilege escalation leading to malware installation, credential harvesting, or lateral movement within the network.
If Mitigated
Limited impact with proper application sandboxing and user privilege restrictions, potentially contained to application crash or limited data exposure.
🎯 Exploit Status
Exploitation requires user interaction (opening malicious file) and understanding of integer underflow manipulation. No public exploits known at this time.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Update to InCopy version 20.1 or later
Vendor Advisory: https://helpx.adobe.com/security/products/incopy/apsb25-10.html
Restart Required: No
Instructions:
1. Open Adobe Creative Cloud application 2. Navigate to 'Apps' tab 3. Find InCopy and click 'Update' 4. Alternatively, download latest version from Adobe website
🔧 Temporary Workarounds
Disable file opening from untrusted sources
allConfigure system policies to prevent opening InCopy files from untrusted locations or email attachments
Application sandboxing
allRun InCopy in restricted environments or sandboxes to limit potential damage from exploitation
🧯 If You Can't Patch
- Implement strict file handling policies: block all .incopy, .icml, and .indd files from untrusted sources
- Use application control solutions to restrict InCopy execution to trusted directories only
🔍 How to Verify
Check if Vulnerable:
Check InCopy version via Help > About InCopy. If version is 20.0, 19.5.1 or earlier, system is vulnerable.Check Version:
On Windows: wmic product where name="Adobe InCopy" get version
On macOS: /Applications/Adobe\ InCopy\ 2024/Adobe\ InCopy\ 2024.app/Contents/MacOS/Adobe\ InCopy\ 2024 --versionVerify Fix Applied:
Verify version is 20.1 or later in Help > About InCopy. Check Creative Cloud shows no available updates for InCopy.📡 Detection & Monitoring
Log Indicators:
- Unexpected InCopy crashes with memory access violations
- InCopy opening files from unusual locations
- Suspicious child processes spawned from InCopy
Network Indicators:
- Outbound connections from InCopy process to unknown IPs
- DNS requests for suspicious domains from InCopy
SIEM Query:
process_name:"incopy.exe" AND (event_id:1000 OR event_id:1001) OR process_parent_name:"incopy.exe" AND process_name NOT IN ("explorer.exe", "svchost.exe")