CVE-2020-27766 – This vulnerability in ImageMagick allows attack... (How to Fix)

Q: What is the severity of CVE-2020-27766?

CVE-2020-27766 has a CVSS score of 7.8 (HIGH). This vulnerability in ImageMagick allows attackers to trigger undefined behavior by submitting specially crafted image files. The flaw involves integer overflow in statistic.c that could cause values outside unsigned long range, potentially leading to crashes or other unpredictable behavior. It affects ImageMagick versions prior to 7.0.8-69.

📋 TL;DR

This vulnerability in ImageMagick allows attackers to trigger undefined behavior by submitting specially crafted image files. The flaw involves integer overflow in statistic.c that could cause values outside unsigned long range, potentially leading to crashes or other unpredictable behavior. It affects ImageMagick versions prior to 7.0.8-69.

💻 Affected Systems

Products:

ImageMagick

Versions: All versions prior to 7.0.8-69

Operating Systems: Linux, Windows, macOS, BSD

Default Config Vulnerable: ⚠️ Yes

Notes: Any application using vulnerable ImageMagick libraries to process images is affected, including web applications, document processors, and image conversion tools.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution or complete system compromise through memory corruption, though this is unlikely given the nature of the vulnerability.

🟠

Likely Case

Application crash or denial of service when processing malicious image files, potentially disrupting image processing services.

🟢

If Mitigated

Minimal impact if proper input validation and sandboxing are implemented, with crashes contained to the ImageMagick process.

🌐 Internet-Facing: MEDIUM - Applications accepting user-uploaded images could be exploited to cause service disruption.

🏢 Internal Only: LOW - Requires local file processing or internal user interaction to trigger.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires crafting a malicious image file that triggers the integer overflow, but no public exploit code has been documented.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: ImageMagick 7.0.8-69 and later

Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1894686

Restart Required: Yes

Instructions:

1. Update ImageMagick to version 7.0.8-69 or later. 2. For Linux systems: Use package manager (apt-get upgrade imagemagick, yum update imagemagick, etc.). 3. For Windows: Download updated binaries from ImageMagick website. 4. Restart any services using ImageMagick.

🔧 Temporary Workarounds

Disable vulnerable image formats

linux

Configure ImageMagick policy.xml to disable processing of potentially malicious image formats

Edit /etc/ImageMagick-7/policy.xml or /etc/ImageMagick-6/policy.xml
Add: <policy domain="coder" rights="none" pattern="*" />

Implement input validation

all

Add file type validation and size limits before passing images to ImageMagick

🧯 If You Can't Patch

Implement strict input validation and file size limits for all image uploads
Run ImageMagick in a sandboxed environment with limited privileges

🔍 How to Verify

Check if Vulnerable:

Check ImageMagick version with: convert --version | grep Version

Check Version:

convert --version | grep Version

Verify Fix Applied:

Verify version is 7.0.8-69 or higher: convert --version | grep 'Version: ImageMagick 7\.0\.8-[6-9][0-9]'

📡 Detection & Monitoring

Log Indicators:

ImageMagick process crashes
Segmentation faults in application logs
Failed image processing operations

Network Indicators:

Multiple failed image uploads from single source
Unusual image file sizes or types being submitted

SIEM Query:

source="*magick*" AND ("segmentation fault" OR "crash" OR "SIGSEGV")

📊 Metadata

CVE ID: CVE-2020-27766

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-190

Published: December 4, 2020

Last Updated: November 21, 2024

🔗 References

https://bugzilla.redhat.com/show_bug.cgi?id=1894686 Exploit,Issue Tracking,Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00030.html Mailing List,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/03/msg00008.html
https://bugzilla.redhat.com/show_bug.cgi?id=1894686 Exploit,Issue Tracking,Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/03/msg00030.html Mailing List,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/03/msg00008.html

📤 Share & Export

📄 Export Markdown 📋 Export JSON

🔗 Related Vulnerabilities

If you're affected by CVE-2020-27766, you might also want to check these: