CVE-2026-106061 in Red Hat
Summary
by MITRE • 10/07/2026
A flaw was found in GIMP’s X cursor (XMC) thumbnail loader. When GIMP generates a thumbnail for a crafted XMC file, it allocates a pixel buffer using a width * height size computed in 32-bit signed arithmetic. If that product overflows, the allocation is smaller than the true image extent. A subsequent GEGL buffer read uses the unwrapped dimensions and performs an out-of-bounds read on the heap (CWE-125), after integer overflow in the size calculation (CWE-190). This can crash GIMP or corrupt process memory.
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Analysis
by VulDB Data Team • 10/07/2026
The vulnerability identified within the GNU Image Manipulation Program, commonly known as GIMP, resides specifically in its X cursor format thumbnail loader component. This security flaw is triggered when the application attempts to generate a visual preview for an input file formatted as an XMC (X Cursor) image. The core of the issue lies in how the software calculates the necessary memory allocation size for the pixel buffer required to render this thumbnail. During this process, GIMP computes the total number of pixels by multiplying the width and height dimensions provided within the crafted file header. This calculation is performed using 32-bit signed integer arithmetic, which imposes a strict upper limit on the magnitude of positive numbers that can be represented without overflow.
When an attacker provides a maliciously constructed XMC file with specific width and height values, it becomes possible to cause an integer overflow during this multiplication operation. Because the calculation wraps around due to the limitations of 32-bit signed arithmetic, the resulting computed size for the buffer allocation is significantly smaller than what would be required to hold the actual image data defined by the unwrapped dimensions. Consequently, GIMP proceeds to allocate a heap memory block that is insufficiently sized relative to the true extent of the image data it intends to process or read from the file. This discrepancy between the allocated size and the expected data volume creates a critical state where subsequent operations will access memory outside the bounds of the allocated buffer.
The operational impact manifests when GIMP attempts to populate this undersized buffer using GEGL, its graph-based image processing library. The software reads pixel data based on the original, unwrapped width and height values rather than the truncated size used for allocation. This leads directly to an out-of-bounds read operation on the heap memory space associated with the process. As described in common vulnerability classifications, this is categorized under CWE-125 Out-of-Bounds Read, which occurs when software reads data from a location beyond the end of a buffer or allocated region. The root cause of this condition is classified as CWE-190 Integer Overflow or Wraparound, highlighting that the failure to properly validate arithmetic results before memory allocation is the primary technical flaw enabling the exploit.
From an operational perspective, this vulnerability allows for potential denial-of-service attacks against users who open maliciously crafted XMC files within GIMP. The out-of-bounds read can corrupt process memory by reading sensitive data from adjacent heap regions or cause immediate application crashes due to segmentation faults when accessing unmapped memory pages. While the primary description emphasizes a read operation, such memory corruption issues often serve as precursors to more severe exploits if combined with other vulnerabilities, potentially leading to information disclosure of internal program state or arbitrary code execution in complex scenarios involving further manipulation of heap metadata. The attack vector is generally local or requires user interaction through file opening mechanisms, placing it within the context of CWE-434 Unrestricted Upload of File with Dangerous Type if the vulnerability were exploited via a web interface accepting uploads, though here it primarily affects desktop application stability and security during direct file handling.
To mitigate this risk, developers must implement rigorous input validation for all dimensional parameters before performing arithmetic operations that determine memory allocation sizes. Specifically, checks should be added to ensure that multiplying width by height does not exceed the maximum value representable by a 32-bit signed integer or any other relevant data type used in the calculation. Additionally, employing safe math libraries or compiler flags that detect overflow conditions can prevent such wraparound errors from occurring silently. For end-users and system administrators, it is advisable to restrict the execution of untrusted image files within isolated environments or sandboxed applications until patches are applied. Keeping GIMP updated with the latest security releases provided by upstream maintainers is critical as these updates typically include fixes for integer overflow handling in file parsers. The vulnerability aligns with ATT&CK techniques related to initial access and defense evasion, specifically where malformed inputs bypass validation checks to trigger unintended code paths or memory states within the application runtime environment.