SDLimage is a library to load images of various formats as SDL surfaces. In dolayersurface() in src/IMGxcf.c, pixel index values from decoded XCF tile data are used directly as colormap indices without validating them against the colormap size (cmnum). A crafted .xcf file with a small colormap and out-of-range pixel indices causes heap out-of-bounds reads of up to 762 bytes past the colormap allocation. Both IMAGEINDEXED code paths are affected (bpp=1 and bpp=2). The leaked heap bytes are written into the output surface pixel data, making them potentially observable in the rendered image. This vulnerability is fixed with commit 996bf12888925932daace576e09c3053410896f8.

SDLimage through 3.4.8 and through 2.8.12 contains a stack out-of-bounds read vulnerability in IMGLoadLBMIO() in src/IMGlbm.c that skips bitplane count validation when HAM mode is set. Attackers can supply a crafted ILBM file with more than 8 HAM bitplanes to read past the colormap stack array, causing crashes or disclosing stack memory.

It was discovered that SDLimage incorrectly handled certain image files. An attacker could possibly use this issue to cause a denial of service or other unspecified impact.