CVE-2026-66757 in Red Hat
Summary
by MITRE • 07/27/2026
A flaw was found in the file-sgi plugin in GIMP. When processing an RLE-compressed SGI image, the plugin allocates memory for a row table. The image header dimensions (ysize and zsize) are read as 16-bit unsigned integers. If a crafted file sets both dimensions to their maximum value (65535), the multiplication ysize * zsize overflows the standard 32-bit int boundary before being passed to calloc. This integer overflow issue results in undefined behavior, aborting the plugin and causing a denial of service.
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Analysis
by VulDB Data Team • 07/27/2026
This vulnerability resides within the file-sgi plugin of the GNU Image Manipulation Program GIMP, representing a classic integer overflow condition that can lead to denial of service through improper memory allocation handling. The flaw specifically manifests when processing RLE-compressed SGI image files where the plugin reads image header dimensions using 16-bit unsigned integers for both ysize and zsize parameters. When these dimensions are manipulated to their maximum possible value of 65535, the multiplication operation ysize * zsize produces a result that exceeds the capacity of a standard 32-bit signed integer, creating an overflow condition that fundamentally breaks the memory allocation logic.
The technical exploitation of this vulnerability occurs at the memory management level where calloc function receives the overflowed value as its size parameter, resulting in either zero allocation or incorrect memory reservation that subsequently leads to plugin termination. This behavior aligns with CWE-190, which specifically addresses integer overflow conditions, and represents a variant of the broader class of integer arithmetic vulnerabilities that can cause undefined behavior in software applications. The vulnerability's impact is limited to denial of service rather than arbitrary code execution, as the overflow occurs in memory allocation rather than control flow manipulation.
From an operational standpoint, this vulnerability creates a reliable denial of service condition for users processing SGI image files through GIMP's file-sgi plugin, potentially affecting graphic designers, photographers, and other creative professionals who rely on this software. The attack vector requires only the preparation of a malicious SGI file with specially crafted header values, making it particularly dangerous in environments where users process untrusted image files from external sources. The vulnerability affects all versions of GIMP that utilize the file-sgi plugin and demonstrates a fundamental lack of input validation for critical image dimensions.
Mitigation strategies should focus on implementing proper integer overflow detection and bounds checking within the file-sgi plugin's memory allocation routines, specifically validating that multiplication operations between 16-bit dimensions do not exceed safe 32-bit integer limits before proceeding with calloc calls. The recommended approach includes adding explicit checks to ensure that ysize * zsize does not exceed INT_MAX or equivalent safety thresholds, and implementing proper error handling that gracefully manages invalid image parameters rather than allowing the overflow to propagate. Additionally, input validation should be enhanced to reject images with dimensions that would result in excessive memory allocation requests, aligning with ATT&CK technique T1203 for Defense Evasion through process injection and manipulation of resource consumption patterns.