CVE-2026-28691 in Prior to
Summary
by MITRE • 03/10/2026
ImageMagick is free and open-source software used for editing and manipulating digital images. Prior to versions 7.1.2-16 and 6.9.13-41, an uninitialized pointer dereference vulnerability exists in the JBIG decoder due to a missing check. This vulnerability is fixed in 7.1.2-16 and 6.9.13-41.
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Analysis
by VulDB Data Team • 04/22/2026
The vulnerability identified as CVE-2026-28691 represents a critical uninitialized pointer dereference flaw within ImageMagick's JBIG decoder component. This issue affects the widely-used open-source image processing software that handles various digital image formats including JBIG which is commonly employed in document imaging and fax applications. The vulnerability stems from inadequate input validation within the JBIG decoding mechanism where the software fails to properly initialize memory pointers before accessing them. This particular flaw falls under CWE-476 which specifically addresses NULL pointer dereference conditions, making it a well-documented category of memory safety issues that have historically led to system instability and potential exploitation opportunities. The JBIG format is particularly sensitive to malformed input due to its complex compression algorithms and metadata structures that require precise memory management during decoding operations.
The operational impact of this vulnerability extends beyond simple application crashes as it creates potential vectors for remote code execution and denial of service attacks. When an attacker crafts a malicious JBIG image file that triggers the uninitialized pointer dereference, the system may experience abrupt termination or unpredictable behavior during the image processing workflow. This presents significant risks in environments where ImageMagick is used for automated image processing, web applications, or document management systems that accept user-uploaded content. The vulnerability's exploitation potential aligns with ATT&CK technique T1203 which covers exploitation of software vulnerabilities, and T1499 which addresses network denial of service attacks through resource exhaustion. Security researchers have noted that such pointer dereference issues often serve as initial footholds for more sophisticated attacks, particularly when the affected software operates with elevated privileges or processes sensitive data.
Mitigation strategies for CVE-2026-28691 require immediate patching of affected ImageMagick installations to versions 7.1.2-16 or 6.9.13-41 where the uninitialized pointer check has been implemented. Organizations should conduct comprehensive vulnerability assessments to identify all systems running vulnerable versions of ImageMagick, particularly those handling user-generated content or processing untrusted image files. Network segmentation and input validation measures should be implemented to prevent malicious JBIG files from reaching image processing systems, while also considering the deployment of web application firewalls that can detect and block suspicious image file uploads. Additionally, system administrators should monitor for unusual process termination patterns or memory access violations that could indicate exploitation attempts, and maintain regular security updates to address similar vulnerabilities in the broader software ecosystem. The fix implemented in the patched versions addresses the root cause by ensuring proper initialization of memory pointers before any dereference operations occur, thereby preventing the null pointer access that previously led to system instability and potential exploitation.