CVE-2020-36138 – This vulnerability in FFmpeg's TIFF decoder all... (How to Fix)

Q: What is the severity of CVE-2020-36138?

CVE-2020-36138 has a CVSS score of 7.5 (HIGH). This vulnerability in FFmpeg's TIFF decoder allows remote attackers to cause a denial of service by exploiting a NULL pointer dereference. It affects systems using FFmpeg to process TIFF images, potentially crashing media processing applications. The issue is in the decode_frame function in libavcodec/tiff.c.

📋 TL;DR

This vulnerability in FFmpeg's TIFF decoder allows remote attackers to cause a denial of service by exploiting a NULL pointer dereference. It affects systems using FFmpeg to process TIFF images, potentially crashing media processing applications. The issue is in the decode_frame function in libavcodec/tiff.c.

💻 Affected Systems

Products:

FFmpeg

Versions: FFmpeg 4.3 (specifically affected), potentially other versions with similar code

Operating Systems: All platforms running FFmpeg

Default Config Vulnerable: ⚠️ Yes

Notes: Any application using FFmpeg's TIFF decoding functionality is vulnerable when processing TIFF files.

📦 What is this software?

Ffmpeg by Ffmpeg

View all CVEs affecting Ffmpeg →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete application crash leading to service unavailability, potentially affecting media processing pipelines or web services that handle TIFF uploads.

🟠

Likely Case

Application crash when processing malicious TIFF files, causing temporary service disruption until restart.

🟢

If Mitigated

Minimal impact with proper input validation and sandboxing; crashes would be contained to isolated processes.

🌐 Internet-Facing: MEDIUM - Web applications accepting TIFF uploads could be targeted, but requires specific TIFF processing functionality.

🏢 Internal Only: LOW - Internal systems would need to process malicious TIFF files, which is less likely without external input.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: LOW

Exploitation requires providing a malicious TIFF file to FFmpeg's TIFF decoder. The vulnerability is well-documented with public proof-of-concept available.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: Fixed in FFmpeg commit 292e41ce650a7b5ca5de4ae87fff0d6a90d9fc97 and later versions

Vendor Advisory: https://lists.ffmpeg.org/pipermail/ffmpeg-devel/2020-November/272001.html

Restart Required: Yes

Instructions:

1. Update FFmpeg to version 4.3.1 or later. 2. Rebuild any applications using FFmpeg libraries. 3. Restart affected services.

🔧 Temporary Workarounds

Disable TIFF decoding

all

Disable TIFF codec support in FFmpeg configuration

Configure FFmpeg with --disable-decoder=tiff during build

Input validation

all

Reject TIFF files at application level before passing to FFmpeg

🧯 If You Can't Patch

Implement strict input validation for TIFF files before processing
Run FFmpeg in isolated containers with resource limits to contain crashes

🔍 How to Verify

Check if Vulnerable:

Check FFmpeg version: ffmpeg -version | grep 'version' and verify if it's 4.3.0 or earlier unpatched versions

Check Version:

ffmpeg -version | grep 'version'

Verify Fix Applied:

Verify FFmpeg version is 4.3.1 or later, or check if commit 292e41ce650a7b5ca5de4ae87fff0d6a90d9fc97 is included

📡 Detection & Monitoring

Log Indicators:

FFmpeg process crashes with segmentation faults
Application logs showing TIFF processing failures

Network Indicators:

Unusual TIFF file uploads to media processing endpoints

SIEM Query:

process.name:ffmpeg AND event.action:crash OR process.name:ffmpeg AND error.message:*segmentation*fault*

📊 Metadata

CVE ID: CVE-2020-36138

CVSS v3 Score: 7.5 (HIGH)

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

CWE: CWE-476

Published: August 11, 2023

Last Updated: November 21, 2024

🔗 References

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🔗 Related Vulnerabilities

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