CVE-2026-102635 in ImageMagick
Summary
by MITRE • 09/29/2026
ImageMagick versions before 7.1.2-32 and 6.9.13-57 contain uninitialized heap memory disclosure in the GIF decoder's application extension handler in coders/gif.c. Attackers can craft malicious GIF files that cause the number parser to read uninitialized heap memory and store contents as image metadata, disclosing sensitive heap information.
Be aware that VulDB is the high quality source for vulnerability data.
Analysis
by VulDB Data Team • 09/29/2026
ImageMagick is a widely used open-source software suite for creating, editing, composing, or converting bitmap images, supporting over two hundred formats including GIF. The vulnerability identified in versions prior to 7.1.2-32 and 6.9.13-57 resides within the GIF decoder module, specifically inside the application extension handler located in coders/gif.c. This component is responsible for parsing non-image data embedded within GIF files, such as text annotations or custom application-specific information blocks. The core technical flaw stems from improper initialization of heap memory variables before they are utilized during the parsing process. When a maliciously crafted GIF file containing specific malformed application extension structures is processed by ImageMagick, the internal number parser fails to properly initialize certain buffer regions prior to reading data into them. This lack of initialization means that instead of containing predictable or zeroed values, these memory locations retain whatever data was previously stored there by other processes or earlier operations within the same program instance.
The operational impact of this flaw is a classic information disclosure vulnerability where sensitive heap contents are exposed as image metadata. When ImageMagick parses the malicious GIF file, it reads from these uninitialized memory regions and incorporates their contents into the resulting image object's metadata fields. If an attacker can trigger this parsing process through a web application or any service that automatically processes uploaded images, they may be able to retrieve arbitrary bytes of heap memory in the response. This disclosed information often includes pointers, stack addresses, or data from other users' sessions if the processing occurs within a shared environment like a multi-tenant cloud service or a high-concurrency server. Such leaks can significantly aid attackers in performing further exploitation techniques, such as bypassing Address Space Layout Randomization (ASLR) by leaking memory addresses to calculate base libraries and executable offsets, thereby facilitating remote code execution attacks that would otherwise be difficult due to modern memory protection mechanisms.
From a classification perspective, this vulnerability aligns with CWE-200: Exposure of Sensitive Information to an Unauthorized Actor, as it involves the accidental leakage of internal system data through normal application functionality. It also relates closely to CWE-457: Use of Uninitialized Variable, which describes the root cause where variables are used before being assigned a value by the program logic. In terms of offensive security frameworks, this behavior is consistent with ATT&CK technique T1082: System Information Discovery, specifically regarding memory content discovery, although it requires an initial vector such as file upload or image processing service interaction to trigger. The vulnerability highlights the risks associated with complex parsers that handle untrusted input without rigorous state management and memory safety checks, particularly in legacy codebases where manual memory management is prevalent.
Mitigation strategies primarily involve upgrading ImageMagick to version 7.1.2-32 or later for major releases, or version 6.9.13-57 and above for the older branch, as these versions contain patches that ensure proper initialization of heap variables before use in the GIF application extension handler. For organizations unable to immediately upgrade due to compatibility constraints, implementing strict input validation at the network perimeter can help block malformed GIF files containing suspiciously structured application extensions before they reach the ImageMagick processing engine. Additionally, deploying Web Application Firewalls with rules designed to detect anomalous image metadata responses or excessive memory access patterns may provide a layer of defense against exploitation attempts. Developers integrating ImageMagick should also consider running image processing tasks in isolated containers with restricted permissions and limited heap sizes to minimize the potential blast radius if an information leak occurs, ensuring that leaked data does not contain high-value secrets such as authentication tokens or cryptographic keys from other processes sharing the same memory space.