"_gx_binres_pixelmap_table_load()" in the GUIX binary resource (theme) loader indexes the pixelmap table with a value read verbatim from the resource file and never bounds it against the table size. A crafted theme drives a write of up to roughly 256 KB past the end of the table. The overflowed buffer is allocated by GUIX itself, through "_gx_system_memory_allocator", rather than supplied by the caller, so the loader corrupts its own arena. The public API "gx_binres_theme_load()" takes no size parameter, so no amount of caller diligence prevents this. Reproduces in the shipped default configuration; "GX_BINARY_RESOURCE_SUPPORT" is enabled by default.