CVE-2021-40568 – A buffer overflow vulnerability in Gpac's MP4 f... (How to Fix)

Q: What is the severity of CVE-2021-40568?

CVE-2021-40568 has a CVSS score of 7.8 (HIGH). A buffer overflow vulnerability in Gpac's MP4 file parser allows attackers to execute arbitrary code or cause denial of service by providing a specially crafted MP4 file. This affects all systems running vulnerable versions of Gpac that process untrusted MP4 files. The vulnerability is in the SVC (Scalable Video Coding) slice parsing functionality.

📋 TL;DR

A buffer overflow vulnerability in Gpac's MP4 file parser allows attackers to execute arbitrary code or cause denial of service by providing a specially crafted MP4 file. This affects all systems running vulnerable versions of Gpac that process untrusted MP4 files. The vulnerability is in the SVC (Scalable Video Coding) slice parsing functionality.

💻 Affected Systems

Products:

Gpac (GPAC Multimedia Framework)

Versions: All versions through 1.0.1

Operating Systems: Linux, Windows, macOS, BSD, Android, iOS

Default Config Vulnerable: ⚠️ Yes

Notes: Any application using Gpac libraries to parse MP4 files is vulnerable. This includes media players, streaming servers, and video processing tools that use Gpac.

📦 What is this software?

Gpac by Gpac

View all CVEs affecting Gpac →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with the privileges of the Gpac process, potentially leading to full system compromise if Gpac runs with elevated privileges.

🟠

Likely Case

Denial of service (crash) of the Gpac application when processing malicious MP4 files, potentially disrupting media processing workflows.

🟢

If Mitigated

Limited impact if Gpac runs in sandboxed environments with minimal privileges and processes only trusted media files.

🌐 Internet-Facing: MEDIUM - Exploitation requires delivering a malicious MP4 file to a vulnerable Gpac instance, which could occur through web applications or media processing services.

🏢 Internal Only: MEDIUM - Internal users could exploit this by providing malicious MP4 files to shared media processing systems or through phishing attacks with embedded media.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

The vulnerability requires crafting a malicious MP4 file with specific SVC encoding parameters. Public references include proof-of-concept discussions in GitHub issues.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Versions after commit f1ae01d745200a258cdf62622f71754c37cb6c30

Vendor Advisory: https://github.com/gpac/gpac/commit/f1ae01d745200a258cdf62622f71754c37cb6c30

Restart Required: Yes

Instructions:

1. Update Gpac to version 1.0.2 or later. 2. For Linux systems: Use package manager (apt/yum) to update gpac package. 3. For source installations: Pull latest code from GitHub and rebuild. 4. Restart any services using Gpac libraries.

🔧 Temporary Workarounds

Disable SVC parsing

all

Modify Gpac configuration to disable parsing of SVC (Scalable Video Coding) streams in MP4 files

Not applicable - requires code modification in av_parsers.c

Input validation

all

Implement strict validation of MP4 files before processing with Gpac libraries

Not applicable - requires application-level changes

🧯 If You Can't Patch

Run Gpac in sandboxed environments with minimal privileges
Implement network segmentation to isolate media processing systems from critical infrastructure

🔍 How to Verify

Check if Vulnerable:

Check Gpac version: gpac -version. If version is 1.0.1 or earlier, system is vulnerable.

Check Version:

gpac -version 2>/dev/null || mp4box -version 2>/dev/null

Verify Fix Applied:

Verify version is 1.0.2 or later: gpac -version | grep -E '1\.0\.2|1\.0\.3|1\.1'

📡 Detection & Monitoring

Log Indicators:

Segmentation faults or crashes in Gpac processes
Unusual memory access patterns in system logs
Failed MP4 file parsing attempts

Network Indicators:

Unusual MP4 file transfers to media processing systems
Multiple failed media processing requests

SIEM Query:

process_name:"gpac" AND (event_type:crash OR exit_code:139)

📊 Metadata

CVE ID: CVE-2021-40568

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-120

Published: January 13, 2022

Last Updated: November 21, 2024

🔗 References

https://github.com/gpac/gpac/commit/f1ae01d745200a258cdf62622f71754c37cb6c30 Patch,Third Party Advisory
https://github.com/gpac/gpac/issues/1900 Exploit,Issue Tracking,Third Party Advisory
https://www.debian.org/security/2023/dsa-5411
https://github.com/gpac/gpac/commit/f1ae01d745200a258cdf62622f71754c37cb6c30 Patch,Third Party Advisory
https://github.com/gpac/gpac/issues/1900 Exploit,Issue Tracking,Third Party Advisory
https://www.debian.org/security/2023/dsa-5411

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🔗 Related Vulnerabilities

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