CVE-2021-20312 – This CVE describes an integer overflow vulnerab... (How to Fix)

Q: What is the severity of CVE-2021-20312?

CVE-2021-20312 has a CVSS score of 7.5 (HIGH). This CVE describes an integer overflow vulnerability in ImageMagick's thumbnail generation function. Attackers can craft malicious image files that trigger undefined behavior when processed by applications using vulnerable ImageMagick versions, potentially causing crashes or denial of service. Systems running ImageMagick 7.0.11 or applications that use it for image processing are affected.

📋 TL;DR

This CVE describes an integer overflow vulnerability in ImageMagick's thumbnail generation function. Attackers can craft malicious image files that trigger undefined behavior when processed by applications using vulnerable ImageMagick versions, potentially causing crashes or denial of service. Systems running ImageMagick 7.0.11 or applications that use it for image processing are affected.

💻 Affected Systems

Products:

ImageMagick

Versions: 7.0.11

Operating Systems: Linux, Unix-like systems, Windows

Default Config Vulnerable: ⚠️ Yes

Notes: Any application using ImageMagick library for image processing is vulnerable when handling crafted images.

📦 What is this software?

Debian Linux by Debian

View all CVEs affecting Debian Linux →

Imagemagick by Imagemagick

View all CVEs affecting Imagemagick →

⚠️ Risk & Real-World Impact

🔴

Worst Case

Complete system crash or denial of service leading to application unavailability, potentially allowing further exploitation through memory corruption.

🟠

Likely Case

Application crash or denial of service when processing malicious images, disrupting image processing functionality.

🟢

If Mitigated

Minimal impact with proper input validation and sandboxing, though processing may still fail.

🌐 Internet-Facing: MEDIUM - Applications accepting user-uploaded images are vulnerable, but exploitation requires specific crafted files.

🏢 Internal Only: LOW - Requires malicious actors with access to upload images to internal systems.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires crafting specific image files; no public exploit code is known.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: 7.0.11-1 and later

Vendor Advisory: https://bugzilla.redhat.com/show_bug.cgi?id=1946742

Restart Required: Yes

Instructions:

1. Update ImageMagick package using system package manager. 2. For Linux: 'sudo apt update && sudo apt upgrade imagemagick' (Debian/Ubuntu) or 'sudo yum update imagemagick' (RHEL/CentOS). 3. Restart applications using ImageMagick.

🔧 Temporary Workarounds

Disable thumbnail generation

all

Configure ImageMagick to skip thumbnail processing for untrusted images

Modify ImageMagick policy.xml to restrict thumbnail operations

Input validation

all

Implement strict file type validation before passing images to ImageMagick

🧯 If You Can't Patch

Implement strict file upload validation and sanitization
Run ImageMagick in sandboxed/containerized environments with limited privileges

🔍 How to Verify

Check if Vulnerable:

Check ImageMagick version: 'convert --version' or 'magick --version' and verify if version is 7.0.11

Check Version:

convert --version | head -1

Verify Fix Applied:

Verify updated version is 7.0.11-1 or later using version command

📡 Detection & Monitoring

Log Indicators:

ImageMagick process crashes
Application errors when processing images
Unusual memory usage patterns

Network Indicators:

Multiple failed image upload attempts
Unusual image file uploads

SIEM Query:

source="*imagemagick*" AND (error OR crash OR "segmentation fault")

📊 Metadata

CVE ID: CVE-2021-20312

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-190

Published: May 11, 2021

Last Updated: November 21, 2024

🔗 References

https://bugzilla.redhat.com/show_bug.cgi?id=1946742 Issue Tracking,Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00000.html Mailing List,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00020.html
https://bugzilla.redhat.com/show_bug.cgi?id=1946742 Issue Tracking,Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2021/06/msg00000.html Mailing List,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2023/05/msg00020.html

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🔗 Related Vulnerabilities

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