{"api_version":"1","generated_at":"2026-08-28T20:42:29+00:00","cve":"CVE-2026-77658","urls":{"html":"https://cve.report/CVE-2026-77658","api":"https://cve.report/api/cve/CVE-2026-77658.json","docs":"https://cve.report/api","cve_org":"https://www.cve.org/CVERecord?id=CVE-2026-77658","nvd":"https://nvd.nist.gov/vuln/detail/CVE-2026-77658"},"summary":{"title":"Dia: dia: stack buffer overflow in bus object via unvalidated handle count in project files","description":"A stack-based buffer overflow vulnerability exists in the Dia diagram editor when processing Network Bus objects from Dia XML project files.\n\nIn 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:\n\n    bus->num_handles = attribute_num_data(attr);\n\nWhen a bus handle is subsequently moved, bus_handle_moved() allocates two temporary arrays on the stack:\n\n    parallel = (real *)g_alloca(num_handles * sizeof(real));\n    perp = (real *)g_alloca(num_handles * sizeof(real));\n\nBecause 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.\n\nAn attacker can embed a Bus object with an excessive bus_handles count in a malicious .dia file. 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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.\n\nThe 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.\n\nAffected versions: Dia 0.98.0 and earlier versions containing this code; issue confirmed on upstream master as of 2026-08-21.\nUpstream report: https://gitlab.gnome.org/GNOME/dia/-/issues/581","Type":"Description","Title":"Dia: dia: stack buffer overflow in bus object via unvalidated ha"}]}}}