CVE-2025-15273
📋 TL;DR
A stack-based buffer overflow vulnerability in FontForge's PFB file parser allows remote attackers to execute arbitrary code when users open malicious PFB files or visit malicious web pages. This affects all FontForge installations that process PFB files. Successful exploitation gives attackers the same privileges as the current user.
💻 Affected Systems
- FontForge
📦 What is this software?
Fontforge by Fontforge
⚠️ Risk & Real-World Impact
Worst Case
Complete system compromise with attacker gaining the same privileges as the user running FontForge, potentially leading to lateral movement, data theft, or ransomware deployment.
Likely Case
Local privilege escalation or malware installation on the user's system when opening malicious PFB files from untrusted sources.
If Mitigated
Limited impact if users only open trusted files and FontForge runs with minimal privileges.
🎯 Exploit Status
Exploitation requires user interaction but the vulnerability is straightforward to exploit once a malicious PFB file is crafted. ZDI has confirmed the vulnerability.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: Check FontForge releases after advisory date
Vendor Advisory: https://github.com/fontforge/fontforge/security/advisories
Restart Required: Yes
Instructions:
1. Check current FontForge version. 2. Update to latest patched version from official repository. 3. Restart FontForge and any dependent services.
🔧 Temporary Workarounds
Disable PFB file processing
allBlock or restrict PFB file processing in FontForge configuration
# Configure FontForge to reject PFB files or use file type restrictions
Sandbox FontForge execution
allRun FontForge in a sandboxed environment with limited privileges
# Use firejail on Linux: firejail --net=none fontforge
# Use Windows Sandbox or similar isolation
🧯 If You Can't Patch
- Implement application whitelisting to prevent unauthorized FontForge execution
- Use endpoint protection that can detect and block malicious PFB files
🔍 How to Verify
Check if Vulnerable:
Check FontForge version and compare against patched releases. Test with known safe PFB files to ensure parsing works.Check Version:
fontforge --versionVerify Fix Applied:
Verify FontForge version is updated to patched release and test PFB file processing functionality.📡 Detection & Monitoring
Log Indicators:
- FontForge crashes with stack overflow errors
- Unexpected child processes spawned from FontForge
- Abnormal memory usage patterns in FontForge
Network Indicators:
- Downloads of PFB files from untrusted sources
- Outbound connections from FontForge process
SIEM Query:
process_name="fontforge" AND (event_id="1000" OR memory_usage>threshold)