CVE-2020-23109
📋 TL;DR
A buffer overflow vulnerability in libheif's color conversion function allows attackers to cause denial of service or information disclosure by processing a malicious HEIF image file. This affects any application using vulnerable versions of libheif to handle HEIF/HEIC image files. The vulnerability can be triggered without authentication by simply opening a crafted file.
💻 Affected Systems
- libheif
- Any software using libheif library (image viewers, editors, web services, etc.)
📦 What is this software?
Libheif by Struktur
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise if the buffer overflow can be controlled to execute arbitrary code, though this would require specific memory layout conditions.
Likely Case
Denial of service (application crash) and potential memory disclosure of sensitive information from the application's memory space.
If Mitigated
Application crash without code execution if ASLR/DEP protections are effective, but information disclosure risk remains.
🎯 Exploit Status
Proof of concept exists in the GitHub issue showing crash reproduction. Weaponization for reliable code execution would require overcoming memory protections and precise control of overflow.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: libheif v1.7.0 and later
Vendor Advisory: https://github.com/strukturag/libheif/issues/207
Restart Required: Yes
Instructions:
1. Update libheif to version 1.7.0 or later. 2. For Linux: Use package manager (apt-get update && apt-get upgrade libheif, yum update libheif, etc.). 3. For Windows/macOS: Download updated version from official repository. 4. Restart any applications using libheif.
🔧 Temporary Workarounds
Disable HEIF processing
allConfigure applications to not process HEIF/HEIC files if not required
Application-specific configuration - no universal command
Input validation and sandboxing
linuxImplement file type validation and process HEIF files in isolated containers
docker run --rm -v /tmp:/tmp image-processor (example only)
🧯 If You Can't Patch
- Implement strict file upload validation to reject or quarantine HEIF files from untrusted sources
- Run vulnerable applications with minimal privileges and memory protection features (ASLR, DEP) enabled
🔍 How to Verify
Check if Vulnerable:
Check libheif version: `libheif --version` or `dpkg -l | grep libheif` or `rpm -qa | grep libheif`. If version is 1.6.2 or earlier, likely vulnerable.Check Version:
libheif --version 2>/dev/null || dpkg -l libheif* 2>/dev/null || rpm -q libheif 2>/dev/null || echo "Check package manager for libheif"Verify Fix Applied:
Confirm libheif version is 1.7.0 or later using same commands. Test with known safe HEIF files to ensure functionality.📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults when processing image files
- Memory access violation errors in application logs
- Unexpected process termination of image processing services
Network Indicators:
- Unusual HEIF file uploads to web services
- Multiple failed image processing attempts
SIEM Query:
Process:Terminated AND (Image:*heif* OR Image:*heic*) AND ExitCode:0xC0000005