CVE-2020-21598
📋 TL;DR
CVE-2020-21598 is a heap buffer overflow vulnerability in libde265 v1.0.4's ff_hevc_put_unweighted_pred_8_sse function that allows remote code execution via a specially crafted HEVC video file. This affects any application or system using the vulnerable libde265 library for HEVC/H.265 video decoding. Attackers can exploit this to execute arbitrary code with the privileges of the application processing the malicious file.
💻 Affected Systems
- libde265
- Applications using libde265 for HEVC decoding
📦 What is this software?
Libde265 by Struktur
⚠️ Risk & Real-World Impact
Worst Case
Remote code execution leading to complete system compromise, data theft, or ransomware deployment on affected systems.
Likely Case
Application crash (denial of service) or limited code execution within the application's context, potentially leading to further system compromise.
If Mitigated
Application crash with no further impact if proper sandboxing, privilege separation, or exploit mitigations are in place.
🎯 Exploit Status
Exploitation requires the victim to process a malicious HEVC video file. The vulnerability is in a widely used library, making it attractive for attackers.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: libde265 v1.0.5 and later
Vendor Advisory: https://github.com/strukturag/libde265/issues/237
Restart Required: Yes
Instructions:
1. Update libde265 to version 1.0.5 or later using your system's package manager. 2. For Debian/Ubuntu: sudo apt update && sudo apt upgrade libde265. 3. For source installations: Download latest version from GitHub and recompile. 4. Restart any applications using libde265.
🔧 Temporary Workarounds
Disable HEVC decoding in applications
allConfigure applications to not use libde265 for HEVC video decoding, or disable HEVC support entirely.
Application-specific configuration required
Use alternative HEVC decoder
linuxReplace libde265 with an alternative HEVC decoder library that is not vulnerable.
Package manager commands to install alternative decoder
🧯 If You Can't Patch
- Implement strict input validation for HEVC video files before processing
- Run applications using libde265 in sandboxed environments with minimal privileges
🔍 How to Verify
Check if Vulnerable:
Check libde265 version: dpkg -l | grep libde265 (Debian/Ubuntu) or rpm -qa | grep libde265 (RHEL/Fedora)Check Version:
libde265 --version 2>/dev/null || dpkg -l libde265 2>/dev/null || rpm -q libde265 2>/dev/nullVerify Fix Applied:
Verify libde265 version is 1.0.5 or higher using version check command📡 Detection & Monitoring
Log Indicators:
- Application crashes with segmentation faults when processing video files
- Unexpected process termination in media-related applications
Network Indicators:
- Unusual outbound connections from media processing applications
- HEVC video file downloads from suspicious sources
SIEM Query:
Process: (libde265 OR media_app) AND Event: (Segmentation fault OR Access violation)🔗 References
- https://cwe.mitre.org/data/definitions/122.html
- https://github.com/strukturag/libde265/issues/237
- https://lists.debian.org/debian-lts-announce/2023/01/msg00020.html
- https://www.debian.org/security/2023/dsa-5346
- https://cwe.mitre.org/data/definitions/122.html
- https://github.com/strukturag/libde265/issues/237
- https://lists.debian.org/debian-lts-announce/2023/01/msg00020.html
- https://www.debian.org/security/2023/dsa-5346
