CVE-2026-25638 Overview
A memory leak vulnerability has been identified in ImageMagick, the widely-used open-source software for editing and manipulating digital images. The vulnerability exists in the WriteMSLImage function within the coders/msl.c file, where resources are allocated but not properly released when the function returns early. This flaw can lead to resource exhaustion and denial of service conditions when processing specially crafted image files.
Critical Impact
Attackers can exploit this memory leak vulnerability to cause resource exhaustion on systems running vulnerable versions of ImageMagick, potentially leading to denial of service conditions affecting image processing services and applications.
Affected Products
- ImageMagick versions prior to 7.1.2-15
- ImageMagick versions prior to 6.9.13-40
- Applications and services that rely on ImageMagick for image processing
Discovery Timeline
- 2026-02-24 - CVE CVE-2026-25638 published to NVD
- 2026-02-24 - Last updated in NVD database
Technical Details for CVE-2026-25638
Vulnerability Analysis
This vulnerability is classified under CWE-401 (Missing Release of Memory after Effective Lifetime), a memory leak weakness that occurs when allocated memory is not properly freed after use. In the context of ImageMagick, the WriteMSLImage function in coders/msl.c allocates resources during image processing operations but fails to release them when the function exits early due to certain conditions.
Memory leaks of this nature can accumulate over time, particularly in server environments where ImageMagick processes multiple images continuously. As memory consumption grows, system performance degrades, and eventually, the application or system may become unresponsive due to resource exhaustion.
Root Cause
The root cause of this vulnerability lies in improper resource management within the WriteMSLImage function. When the function encounters certain error conditions or processing paths that cause it to return early, the cleanup code responsible for deallocating previously allocated resources is bypassed. This results in memory that remains allocated but is no longer accessible or usable by the application, constituting a memory leak.
Attack Vector
The vulnerability can be exploited remotely over a network without requiring authentication or user interaction. An attacker can submit specially crafted image files to an application that uses ImageMagick for processing. By repeatedly triggering the vulnerable code path, the attacker can cause progressive memory consumption that eventually leads to denial of service.
The attack is particularly effective against:
- Web applications that accept user-uploaded images
- Image processing pipelines and batch conversion services
- Content management systems with automated image handling
- APIs that expose ImageMagick functionality
Detection Methods for CVE-2026-25638
Indicators of Compromise
- Gradual increase in memory consumption by ImageMagick processes over time
- Application crashes or out-of-memory errors during image processing operations
- Degraded system performance when handling MSL image format files
- Process terminations due to memory limits being exceeded
Detection Strategies
- Monitor memory usage patterns of processes invoking ImageMagick libraries
- Implement resource usage alerts for abnormal memory growth in image processing services
- Review application logs for repeated errors related to MSL image processing
- Deploy runtime application self-protection (RASP) solutions to detect resource exhaustion attacks
Monitoring Recommendations
- Configure memory usage thresholds and alerts for ImageMagick processes
- Implement process-level resource limits to contain the impact of memory leaks
- Establish baseline memory consumption metrics for normal image processing operations
- Enable detailed logging for image processing operations to identify suspicious patterns
How to Mitigate CVE-2026-25638
Immediate Actions Required
- Upgrade ImageMagick to version 7.1.2-15 or later for the 7.x branch
- Upgrade ImageMagick to version 6.9.13-40 or later for the 6.x branch
- Implement resource limits for ImageMagick processes using system controls
- Consider temporarily disabling MSL format processing if not required
- Review and restrict file types accepted by image processing applications
Patch Information
ImageMagick has released patches addressing this memory leak vulnerability. The fixes are included in versions 7.1.2-15 and 6.9.13-40. For detailed information about the security fix, refer to the ImageMagick Security Advisory.
Organizations should prioritize updating to the patched versions to eliminate the vulnerability. The patch ensures proper resource cleanup in the WriteMSLImage function, preventing memory leaks regardless of the execution path taken.
Workarounds
- Implement process recycling to periodically restart ImageMagick worker processes
- Configure cgroup memory limits to prevent system-wide impact from memory exhaustion
- Use ImageMagick policy files to disable MSL format processing if not needed
- Deploy external monitoring to automatically restart services experiencing memory growth
# Configuration example - Disable MSL format in ImageMagick policy.xml
# Add to /etc/ImageMagick-7/policy.xml or equivalent location
# <policy domain="coder" rights="none" pattern="MSL" />
# Set memory limits for ImageMagick processes using cgroups
systemctl set-property imagemagick.service MemoryMax=2G
# Alternatively, configure resource limits in the policy file
# <policy domain="resource" name="memory" value="256MiB"/>
# <policy domain="resource" name="map" value="512MiB"/>
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
