CVE-2020-26664 – This vulnerability allows attackers to execute ... (How to Fix)

Q: What is the severity of CVE-2020-26664?

CVE-2020-26664 has a CVSS score of 7.8 (HIGH). This vulnerability allows attackers to execute arbitrary code on systems running vulnerable versions of VLC media player by tricking users into opening a specially crafted .mkv file. The heap-based buffer overflow can lead to remote code execution. All users of VLC 3.0.11 and potentially earlier versions are affected.

📋 TL;DR

This vulnerability allows attackers to execute arbitrary code on systems running vulnerable versions of VLC media player by tricking users into opening a specially crafted .mkv file. The heap-based buffer overflow can lead to remote code execution. All users of VLC 3.0.11 and potentially earlier versions are affected.

💻 Affected Systems

Products:

VideoLAN VLC media player

Versions: 3.0.11 and potentially earlier versions

Operating Systems: Windows, Linux, macOS, Unix-like systems

Default Config Vulnerable: ⚠️ Yes

Notes: All default installations of affected VLC versions are vulnerable when processing .mkv files.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with system-level privileges, potentially leading to complete system compromise, data theft, or ransomware deployment.

🟠

Likely Case

Application crash (denial of service) or limited code execution within the VLC process context.

🟢

If Mitigated

Application crash with no further impact if proper sandboxing or exploit mitigations are in place.

🌐 Internet-Facing: MEDIUM - Requires user interaction to open malicious file, but files can be distributed via websites, email, or downloads.

🏢 Internal Only: MEDIUM - Same attack vector applies internally through file shares, email attachments, or compromised internal websites.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploit requires user to open malicious .mkv file. Public proof-of-concept exists in the referenced gist.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 3.0.12 and later

Vendor Advisory: http://videolan.com/security/sb-vlc3012.html

Restart Required: No

Instructions:

1. Download latest VLC version from official website. 2. Uninstall old version. 3. Install new version. 4. Verify version is 3.0.12 or higher.

🔧 Temporary Workarounds

Disable MKV file association

all

Prevent VLC from automatically opening .mkv files

Windows: Control Panel > Default Programs > Associate file type > Change .mkv to another player
Linux: update-alternatives --config x-www-browser
macOS: Right-click .mkv > Get Info > Open With > Change All

Use application sandboxing

all

Run VLC in restricted environment

Linux: firejail vlc
Windows: Sandboxie
macOS: sandbox-exec

🧯 If You Can't Patch

Block .mkv files at network perimeter/email filters
Educate users not to open untrusted media files

🔍 How to Verify

Check if Vulnerable:

Check VLC version: Help > About (GUI) or vlc --version (CLI). If version is 3.0.11 or earlier, system is vulnerable.

Check Version:

vlc --version | head -1

Verify Fix Applied:

Confirm VLC version is 3.0.12 or higher using same commands.

📡 Detection & Monitoring

Log Indicators:

VLC crash logs
Application error events mentioning VLC
Heap corruption errors in system logs

Network Indicators:

Downloads of .mkv files from untrusted sources
Unusual outbound connections after VLC execution

SIEM Query:

EventID=1000 OR EventID=1001 AND ProcessName="vlc.exe" OR Source="VLC" AND Keywords="Crash"

📊 Metadata

CVE ID: CVE-2020-26664

CVSS v3 Score: 7.8 (HIGH)

CVSS Vector: CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CWE: CWE-787

Published: January 8, 2021

Last Updated: November 21, 2024

🔗 References

http://videolan.com Product,Vendor Advisory
http://vlc.com Third Party Advisory
https://gist.githubusercontent.com/henices/db11664dd45b9f322f8514d182aef5ea/raw/d56940c8bf211992bf4f3309a85bb2b69383e511/CVE-2020-26664.txt Exploit,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/06/msg00012.html Mailing List,Third Party Advisory
https://security.gentoo.org/glsa/202101-37 Third Party Advisory
https://www.debian.org/security/2021/dsa-4834 Third Party Advisory
http://videolan.com Product,Vendor Advisory
http://vlc.com Third Party Advisory
https://gist.githubusercontent.com/henices/db11664dd45b9f322f8514d182aef5ea/raw/d56940c8bf211992bf4f3309a85bb2b69383e511/CVE-2020-26664.txt Exploit,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2022/06/msg00012.html Mailing List,Third Party Advisory
https://security.gentoo.org/glsa/202101-37 Third Party Advisory
https://www.debian.org/security/2021/dsa-4834 Third Party Advisory

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🔗 Related Vulnerabilities

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