SDL_image is a library to load images of various formats as SDL surfaces. In do_layer_surface() in src/IMG_xcf.c, pixel index values from decoded XCF tile data are used directly as colormap indices without validating them against the colormap size (cm_num). 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 IMAGE_INDEXED 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.
Attack Parameters
Attack Vector
Network
Can be exploited remotely
Attack Complexity
Low
Easy to exploit
Privileges Required
None
No privileges needed
User Interaction
Required
User action required
Impact Assessment
Confidentiality
High
Complete data leak
Integrity
None
No data modification
Availability
Low
Partial disruption
CVSS Vector v3.1