CVE-2020-27755 in ImageMagick
Summary
by MITRE • 12/09/2020
in SetImageExtent() of /MagickCore/image.c, an incorrect image depth size can cause a memory leak because the code which checks for the proper image depth size does not reset the size in the event there is an invalid size. The patch resets the depth to a proper size before throwing an exception. The memory leak can be triggered by a crafted input file that is processed by ImageMagick and could cause an impact to application reliability, such as denial of service. This flaw affects ImageMagick versions prior to 7.0.9-0.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/14/2020
The vulnerability described in CVE-2020-27755 represents a critical memory management flaw within ImageMagick's image processing pipeline, specifically within the SetImageExtent() function located in MagickCore/image.c. This issue stems from inadequate validation mechanisms that fail to properly handle invalid image depth specifications during file processing operations. The flaw manifests when an attacker crafts a malicious input file that deliberately contains incorrect image depth parameters, which then triggers improper memory allocation behavior within the software's internal processing routines.
The technical implementation of this vulnerability involves a specific code path where the image depth validation logic does not adequately reset the depth parameter when an invalid size is detected. This failure creates a memory leak condition because the system allocates memory based on the malformed depth specification but fails to properly clean up or reset the allocation state before proceeding to throw an exception. The CWE-459 identifier applies here as this represents a partially initialized resource issue where memory is allocated but not properly released due to incomplete error handling. The vulnerability operates at the intersection of memory management and input validation, creating a scenario where malformed input can cause resource exhaustion.
The operational impact of this vulnerability extends beyond simple memory consumption to potentially compromise application reliability and system stability. When processed through ImageMagick's image handling pipeline, the crafted input file can trigger repeated memory allocation failures that accumulate over time, leading to progressive resource exhaustion. This memory leak condition directly maps to the ATT&CK technique T1499.004 for resource exhaustion, where adversaries can exploit software vulnerabilities to consume system resources and cause denial of service conditions. Applications that rely on ImageMagick for image processing, particularly those handling untrusted input such as web applications, file upload systems, or content management platforms, become vulnerable to sustained denial of service attacks.
The remediation approach implemented in the patch addresses this vulnerability by ensuring that the image depth parameter is explicitly reset to a valid size before any exception handling occurs. This defensive programming technique prevents the accumulation of invalid state that leads to memory leaks. The fix specifically targets ImageMagick versions prior to 7.0.9-0, indicating that this vulnerability was introduced in earlier releases and subsequently addressed through proper state management. Organizations should prioritize upgrading to ImageMagick 7.0.9-0 or later versions to mitigate this risk, while also implementing input validation measures to prevent processing of potentially malicious image files. The vulnerability demonstrates the importance of proper resource cleanup in error handling paths and highlights how seemingly minor validation flaws can lead to significant reliability issues in image processing libraries that are widely deployed across enterprise environments.