Gdk‑pixbuf: heap‑buffer‑overflow in gdk‑pixbuf

A flaw exists in gdk‑pixbuf within the gdk_pixbuf__jpeg_image_load_increment function (io-jpeg.c) and in glib’s g_base64_encode_step (glib/gbase64.c). When processing maliciously crafted JPEG images, a heap buffer overflow can occur during Base64 encoding, allowing out-of-bounds reads from heap memory, potentially causing application crashes or arbitrary code execution.