CVE-2026-77658

*** Pendiente de traducción *** A stack-based buffer overflow vulnerability exists in the Dia diagram editor when processing Network Bus objects from Dia XML project files.<br /> <br /> In objects/network/bus.c, bus_load() reads the number of bus handles from the file attribute "bus_handles" using attribute_num_data() without validating an upper bound:<br /> <br /> bus-&gt;num_handles = attribute_num_data(attr);<br /> <br /> When a bus handle is subsequently moved, bus_handle_moved() allocates two temporary arrays on the stack:<br /> <br /> parallel = (real *)g_alloca(num_handles * sizeof(real));<br /> perp = (real *)g_alloca(num_handles * sizeof(real));<br /> <br /> Because num_handles is fully attacker-controlled via the project file, sufficiently large values (for example 262144 or higher) cause g_alloca() to consume more stack space than the default thread stack limit (typically 8 MB on Linux), resulting in stack overflow, SIGSEGV, and potential stack frame / return-address corruption.<br /> <br /> An attacker can embed a Bus object with an excessive bus_handles count in a malicious .dia file. Exploitation requires the victim to open the file in Dia (file dialog, command line, or file association) and trigger handle manipulation (moving a bus handle), which exercises the vulnerable code path.<br /> <br /> The identical g_alloca pattern is present in objects/Misc/tree.c (copied from bus.c) and is likely vulnerable to the same class of attack via Tree objects.<br /> <br /> Affected versions: Dia 0.98.0 and earlier versions containing this code; issue confirmed on upstream master as of 2026-08-21.<br /> Upstream report: https://gitlab.gnome.org/GNOME/dia/-/issues/581