CVE-2021-40263 – A heap overflow vulnerability in FreeImage 1.18... (How to Fix)

Q: What is the severity of CVE-2021-40263?

CVE-2021-40263 has a CVSS score of 8.8 (HIGH). A heap overflow vulnerability in FreeImage 1.18.0 allows attackers to execute arbitrary code or cause denial of service by processing specially crafted TIFF files. This affects any application or system using the vulnerable FreeImage library for TIFF image processing. The vulnerability is exploitable remotely if the application processes untrusted TIFF files.

📋 TL;DR

A heap overflow vulnerability in FreeImage 1.18.0 allows attackers to execute arbitrary code or cause denial of service by processing specially crafted TIFF files. This affects any application or system using the vulnerable FreeImage library for TIFF image processing. The vulnerability is exploitable remotely if the application processes untrusted TIFF files.

💻 Affected Systems

Products:

FreeImage

Versions: FreeImage 1.18.0 specifically (though earlier versions may have similar issues)

Operating Systems: All operating systems where FreeImage is used

Default Config Vulnerable: ⚠️ Yes

Notes: Any application linking against FreeImage 1.18.0 and using TIFF processing functionality is vulnerable.

📦 What is this software?

Freeimage by Freeimage Project

View all CVEs affecting Freeimage →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution leading to complete system compromise, data theft, or ransomware deployment.

🟠

Likely Case

Application crash (denial of service) with potential for limited code execution depending on exploit sophistication.

🟢

If Mitigated

Application crash without code execution if memory protections like ASLR are effective.

🌐 Internet-Facing: HIGH if applications process user-uploaded TIFF files without validation.

🏢 Internal Only: MEDIUM if TIFF processing occurs internally with controlled inputs.

🎯 Exploit Status

Public PoC: ⚠️ Yes

Weaponized: LIKELY

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Proof-of-concept exists in bug reports. Exploitation requires crafting malicious TIFF files.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: FreeImage 1.18.1 or later

Vendor Advisory: https://sourceforge.net/p/freeimage/bugs/336/

Restart Required: Yes

Instructions:

1. Download FreeImage 1.18.1 or later from official source. 2. Replace existing FreeImage library files. 3. Recompile/redeploy applications using FreeImage. 4. Restart affected services.

🔧 Temporary Workarounds

Disable TIFF plugin

linux

Remove or disable FreeImage's TIFF plugin to prevent exploitation via TIFF files.

mv /usr/lib/libfreeimageplus.so.3 /usr/lib/libfreeimageplus.so.3.disabled
ldconfig

Input validation

all

Implement strict validation of TIFF files before processing with FreeImage.

🧯 If You Can't Patch

Implement network segmentation to isolate systems using FreeImage
Deploy application allowlisting to prevent unauthorized code execution

🔍 How to Verify

Check if Vulnerable:

Check FreeImage version: ldd --version on linked applications or check library files.

Check Version:

strings /usr/lib/libfreeimage.so.3 | grep -i version

Verify Fix Applied:

Verify FreeImage version is 1.18.1 or later and test with known malicious TIFF samples.

📡 Detection & Monitoring

Log Indicators:

Application crashes when processing TIFF files
Memory access violation errors in application logs

Network Indicators:

Unusual TIFF file uploads to web applications
TIFF files with abnormal structure/size

SIEM Query:

source="application.log" AND ("segmentation fault" OR "access violation") AND "TIFF"

📊 Metadata

CVE ID: CVE-2021-40263

CVSS v3 Score: 8.8 (HIGH)

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

CWE: CWE-787

Published: August 22, 2023

Last Updated: November 21, 2024

🔗 References

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2021-40263, you might also want to check these: