CVE-2026-28690: ImageMagick Buffer Overflow Vulnerability

CVE-2026-28690 Overview

A stack buffer overflow vulnerability has been identified in ImageMagick, the widely-used open-source software for editing and manipulating digital images. The vulnerability exists in the MNG (Multiple-image Network Graphics) encoder component, where missing bounds checks allow an attacker to corrupt the stack with attacker-controlled data. This flaw affects ImageMagick versions prior to 7.1.2-16 and 6.9.13-41.

Critical Impact

Successful exploitation of this stack buffer overflow could allow attackers to corrupt stack memory, potentially leading to code execution or denial of service when processing maliciously crafted MNG image files.

Affected Products

• ImageMagick versions prior to 7.1.2-16
• ImageMagick versions prior to 6.9.13-41
• All platforms running vulnerable ImageMagick installations (Linux, Windows, macOS)

Discovery Timeline

• 2026-03-10 - CVE-2026-28690 published to NVD
• 2026-03-11 - Last updated in NVD database

Technical Details for CVE-2026-28690

Vulnerability Analysis

This vulnerability is classified as CWE-121 (Stack-based Buffer Overflow), a memory corruption vulnerability that occurs when data is written beyond the boundaries of a fixed-length stack buffer. In the context of ImageMagick's MNG encoder, the flaw stems from insufficient validation of input data during the encoding process.

The MNG format is a complex image format that supports multiple frames and animation. When ImageMagick processes or converts images to MNG format, the encoder handles various data structures that require proper bounds checking. The absence of these checks creates a condition where oversized or malformed input can overflow the allocated stack buffer.

This is a local attack vector vulnerability requiring user interaction, meaning an attacker would need to convince a victim to process a malicious image file. However, given ImageMagick's widespread use in automated image processing pipelines, web applications, and content management systems, the attack surface is substantial.

Root Cause

The root cause of CVE-2026-28690 lies in missing bounds checks within the MNG encoder functionality. When processing image data for MNG encoding, the affected code paths fail to validate that input data fits within the allocated stack buffer before writing. This allows attacker-controlled data to overflow the buffer boundaries and overwrite adjacent stack memory, including potentially sensitive data such as return addresses and saved registers.

Attack Vector

The vulnerability requires local access and user interaction to exploit. An attacker would typically craft a malicious image file designed to trigger the buffer overflow when processed by ImageMagick's MNG encoder. Attack scenarios include:

• Uploading a malicious image to a web application that uses ImageMagick for image conversion
• Sending a crafted image file via email or messaging to trick users into opening it with ImageMagick-based tools
• Placing malicious images in shared directories processed by automated ImageMagick scripts
• Exploiting CI/CD pipelines or build systems that process untrusted image content

The vulnerability affects the integrity and availability of systems, with potential for high impact on both. When the stack is corrupted with attacker-controlled data, it could lead to arbitrary code execution, application crashes, or denial of service conditions.

Detection Methods for CVE-2026-28690

Indicators of Compromise

• Unexpected crashes or segmentation faults in ImageMagick processes during MNG file processing
• Abnormal memory access patterns or stack corruption errors in system logs
• Presence of unusually structured or oversized MNG files in upload directories or processing queues
• ImageMagick error messages indicating buffer overruns or memory violations

Detection Strategies

• Monitor ImageMagick process behavior for abnormal terminations or memory access violations
• Implement file integrity monitoring on directories containing ImageMagick configuration files
• Deploy endpoint detection solutions capable of identifying stack buffer overflow exploitation attempts
• Use application-level logging to track MNG encoding operations and detect anomalies

Monitoring Recommendations

• Enable verbose logging in ImageMagick to capture detailed processing information
• Configure system-level crash handlers to collect core dumps for forensic analysis
• Implement real-time monitoring of ImageMagick process resource usage and crash rates
• Set up alerts for unusual file processing patterns or high volumes of MNG conversions

How to Mitigate CVE-2026-28690

Immediate Actions Required

• Upgrade ImageMagick to version 7.1.2-16 or later for the 7.x branch
• Upgrade ImageMagick to version 6.9.13-41 or later for the 6.x branch
• Audit systems for ImageMagick installations and prioritize patching internet-facing or high-risk systems
• Review ImageMagick policy.xml configurations to restrict MNG processing if not required

Patch Information

ImageMagick has released security patches addressing this vulnerability. Users should upgrade to the fixed versions (7.1.2-16 for the 7.x series or 6.9.13-41 for the 6.x series) immediately. Detailed information about the vulnerability and patch can be found in the ImageMagick Security Advisory.

Package managers for major Linux distributions should have updated packages available. Users can also compile from source using the latest tagged releases from the official ImageMagick repository.

Workarounds

• Disable MNG encoding in ImageMagick's policy.xml if MNG format is not required for your use case
• Implement input validation to reject MNG files before they reach ImageMagick processing
• Use containerization or sandboxing to isolate ImageMagick processing from critical system components
• Configure resource limits in policy.xml to constrain ImageMagick's memory and processing capabilities

# Example policy.xml configuration to disable MNG encoding
# Add to /etc/ImageMagick-7/policy.xml or equivalent location
cat >> /etc/ImageMagick-7/policy.xml << 'EOF'
<policymap>
  <!-- Disable MNG format processing as a mitigation for CVE-2026-28690 -->
  <policy domain="coder" rights="none" pattern="MNG" />
</policymap>
EOF