CVE-2020-25690
📋 TL;DR
CVE-2020-25690 is a heap-based out-of-bounds write vulnerability in FontForge that allows attackers to crash applications or execute arbitrary code by crafting malicious SFD font files. This affects users who process untrusted font files with vulnerable FontForge versions. The vulnerability impacts confidentiality, integrity, and availability of affected systems.
💻 Affected Systems
- FontForge
📦 What is this software?
Fontforge by Fontforge
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution with system compromise, allowing attackers to install malware, exfiltrate data, or pivot to other systems.
Likely Case
Application crashes leading to denial of service, with potential for limited code execution in specific exploitation scenarios.
If Mitigated
Minimal impact if systems don't process untrusted font files or have proper input validation in place.
🎯 Exploit Status
Exploitation requires user interaction to open malicious font files. No authentication needed for local exploitation.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 20200314 and later
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1893188
Restart Required: No
Instructions:
1. Update FontForge to version 20200314 or later. 2. For package managers: Use system package manager (apt, yum, brew) to update. 3. For source builds: Download latest version from official repository and recompile.
🔧 Temporary Workarounds
Restrict font file processing
allLimit FontForge usage to trusted font files only and implement file validation
🧯 If You Can't Patch
- Implement strict file validation for SFD files before processing
- Use alternative font processing tools for untrusted files
🔍 How to Verify
Check if Vulnerable:
Check FontForge version with 'fontforge --version' and verify it's older than 20200314Check Version:
fontforge --versionVerify Fix Applied:
Confirm version is 20200314 or newer with 'fontforge --version'📡 Detection & Monitoring
Log Indicators:
- FontForge crash logs
- Memory access violation errors
- Unexpected process termination
Network Indicators:
- Unusual font file downloads to systems running FontForge
SIEM Query:
Process:fontforge AND (EventID:1000 OR ExceptionCode:c0000005)