GIMP File-Fits Plugin - CraftedSignal Threat Feedhttps://feed.craftedsignal.io/products/gimp-file-fits-plugin/Trending threats, MITRE ATT&CK coverage, and detection metadata. Fed continuously.Hugoenhello@craftedsignal.iohello@craftedsignal.ioMon, 27 Jul 2026 19:46:29 +0000CVE-2026-66758 - Integer Overflow in GIMP's file-fits Plugin Leads to RCEhttps://feed.craftedsignal.io/briefs/2026-07-cve-2026-66758-gimp-file-fits/Mon, 27 Jul 2026 19:46:29 +0000hello@craftedsignal.iohttps://feed.craftedsignal.io/briefs/2026-07-cve-2026-66758-gimp-file-fits/A vulnerability in the GIMP file-fits plugin allows for an integer overflow when processing crafted FITS image files, occurring during memory allocation calculations for width and height, which leads to an undersized heap-based buffer, and subsequent writing of pixel data to this buffer causes a heap-based buffer overflow and memory corruption, resulting in arbitrary code execution or a denial of service.A high-severity vulnerability, identified as CVE-2026-66758, exists in the file-fits plugin of GIMP, a popular open-source image editor. This flaw arises when the plugin processes specially crafted FITS (Flexible Image Transport System) image files. Specifically, the plugin uses signed 32-bit integers to calculate memory allocation sizes for image width and height. Attackers can create a FITS file with extremely large width and height values such that their product exceeds the maximum value for a signed 32-bit integer, leading to an integer overflow. This overflow results in the allocation of an undersized heap-based buffer. When the cfitsio library subsequently attempts to write a full row of pixel data into this insufficient buffer, a heap-based buffer overflow occurs, causing memory corruption. This critical vulnerability can be exploited by an attacker to achieve arbitrary code execution or cause a denial of service on a vulnerable system.

Attack Chain

  1. Attacker crafts a malicious FITS image file, embedding specific large width and height values in its header designed to trigger an integer overflow.
  2. The malicious FITS file is delivered to a victim, typically via social engineering methods such as email attachments, malicious downloads from compromised websites, or shared network drives.
  3. The victim opens the malicious FITS file using the GIMP application.
  4. GIMP's file-fits plugin is invoked to parse the FITS image, specifically reading the width and height parameters from the file header.
  5. During memory allocation calculation for the image pixel data, the plugin multiplies the crafted large width and height values, leading to an integer overflow due to the use of signed 32-bit integers.
  6. This integer overflow causes the plugin to allocate an undersized heap-based buffer, significantly smaller than required for the actual image data.
  7. The cfitsio library attempts to write a full row of pixels into this undersized buffer, which results in a heap-based buffer overflow and memory corruption.
  8. Successful memory corruption can lead to the execution of arbitrary code on the victim's system, granting the attacker control, or cause a denial of service by crashing the GIMP application.

Impact

The successful exploitation of CVE-2026-66758 can lead to severe consequences for users of vulnerable GIMP installations. The primary impacts are arbitrary code execution, allowing an attacker to run malicious commands or install malware on the victim's system, and denial of service, causing the GIMP application to crash and potentially disrupting user workflow. While specific victim counts or targeted sectors are not detailed, any user processing untrusted FITS files with a vulnerable version of GIMP is at risk.

Recommendation

  • Patch CVE-2026-66758 immediately by upgrading GIMP and its file-fits plugin to the latest secure version.
  • Educate users about the risks of opening FITS image files from untrusted or unverified sources, as a crafted malicious file is the delivery vector for CVE-2026-66758.
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