Bug 2391093 (CVE-2025-57803)

A flaw was found in ImageMagick. In 32-bit builds, the Bitmap encoder miscalculates the stride value when processing images with very large with. Mathematically, the stride value is calculated as width multiplied by 3 but the theoretical limit of such value is 2^32 for 32-bit integers. So, if this value is exceeded, the encoder uses modulo to convert it down and then takes the smaller value as the actual stride length. This is problematic because the pixel data starts to overlap when being added to the buffer due to the small stride value messing up the rows. This heap buffer overflow allows an attacker to cause a denial of service or, with crafted input, potentially execute arbitrary code.