CVE-2020-27844
📋 TL;DR
CVE-2020-27844 is an out-of-bounds write vulnerability in OpenJPEG's t2.c file that allows attackers to compromise confidentiality, integrity, and availability by providing crafted input during image conversion/encoding. This affects any system using OpenJPEG versions before 2.4.0 for processing JPEG2000 images. Applications that parse untrusted JPEG2000 files are particularly vulnerable.
💻 Affected Systems
- OpenJPEG
- Applications using OpenJPEG library (e.g., image viewers, converters, document processors)
📦 What is this software?
Openjpeg by Uclouvain
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or service disruption
Likely Case
Application crash (denial of service) or limited memory corruption
If Mitigated
Contained crash of the OpenJPEG process without system-wide impact
🎯 Exploit Status
Proof-of-concept available in Red Hat Bugzilla; exploitation requires feeding malicious JPEG2000 files
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: OpenJPEG 2.4.0 and later
Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1907521
Restart Required: Yes
Instructions:
1. Update OpenJPEG to version 2.4.0 or later. 2. For Linux distributions: Use package manager (apt/yum/dnf) to update libopenjp2 package. 3. Rebuild any applications statically linked to OpenJPEG. 4. Restart affected services.
🔧 Temporary Workarounds
Disable JPEG2000 processing
allConfigure applications to reject or not process JPEG2000 image formats
Input validation
allImplement strict file type validation before passing to OpenJPEG
🧯 If You Can't Patch
- Isolate OpenJPEG usage to dedicated, restricted containers/VMs
- Implement network segmentation and strict access controls for systems using OpenJPEG
🔍 How to Verify
Check if Vulnerable:
Check OpenJPEG version: openjp2 --version or dpkg -l | grep libopenjp2 or rpm -q openjpeg2Check Version:
openjp2 --version 2>/dev/null || dpkg -l libopenjp2* 2>/dev/null || rpm -q openjpeg2 2>/dev/nullVerify Fix Applied:
Confirm version is 2.4.0 or higher and test with known malicious JPEG2000 samples📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults in OpenJPEG functions
- Unexpected process termination when processing image files
Network Indicators:
- Unusual uploads of JPEG2000 files to web applications
- Exploitation attempts via image upload endpoints
SIEM Query:
process_name:"openjp2" AND (event_type:crash OR exit_code:139)🔗 References
- https://bugzilla.redhat.com/show_bug.cgi?id=1907521
- https://lists.debian.org/debian-lts-announce/2021/02/msg00011.html
- https://security.gentoo.org/glsa/202101-29
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
- https://bugzilla.redhat.com/show_bug.cgi?id=1907521
- https://lists.debian.org/debian-lts-announce/2021/02/msg00011.html
- https://security.gentoo.org/glsa/202101-29
- https://www.oracle.com//security-alerts/cpujul2021.html
- https://www.oracle.com/security-alerts/cpuApr2021.html
