Didn't see this bug reported after a quick search.

When burning a CD-R and the size of the imagefile is greater than that of CD-R capacity wrong size is shown in Image Burning setup.

In my case trying to burn image file of size 834Mb on a 700Mb CD-R shows 18.4EB of free space and allows burning to continue and obviously fails later on (this continuing was obvious fail on my part and not paying attention).

This problem seems to happen on line:
https://git.gnome.org/browse/brasero/tree/libbrasero-burn/brasero-dest-selection.c#n727

and the use of g_format_size to get the string in line 721:
size_string = g_format_size (size_bytes - session_bytes);

as g_format_size according to docs takes (guint64 size) and size_bytes and session_bytes both are defined as goffset and in glib:
typedef gint64 goffset
typedef signed long gint64;

there lies the problem unless I am totally mistaken. There seems to be other similar code snippets but unfortunately I don't currently have time to go this trough myself.

Screenshot taken on ubuntu 13.10, brasero 3.8.

Thanks,
 - Sami