A stack-based buffer overflow vulnerability exists in the Dia diagram editor when processing Network Bus objects from Dia XML project files. 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: bus->num_handles = attribute_num_data(attr); When a bus handle is subsequently moved, bus_handle_moved() allocates two temporary arrays on the stack: parallel = (real *)g_alloca(num_handles * sizeof(real)); perp = (real *)g_alloca(num_handles * sizeof(real)); 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. 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. 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. Affected versions: Dia 0.98.0 and earlier versions containing this code; issue confirmed on upstream master as of 2026-08-21. Upstream report: https://gitlab.gnome.org/GNOME/dia/-/issues/581
| Métrique | Valeur | Interprétation |
|---|---|---|
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AV (Vecteur d'Attaque)
Attack Vector
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Local (L)
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Exploit nécessite un accès local au système |
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AC (Complexité d'Attaque)
Attack Complexity
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Low (L)
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Peu de conditions requises pour exploiter |
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PR (Privilèges Requis)
Privileges Required
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None (N)
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Aucune authentification requise |
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UI (Interaction Utilisateur)
User Interaction
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Required (R)
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NĂ©cessite une action utilisateur (clic lien, ouverture fichier, etc.) |
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S (Périmètre)
Scope
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Unchanged (U)
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Impact reste dans le périmètre du composant compromis |
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C (Impact Confidentialité)
Confidentiality Impact
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High (H)
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Divulgation totale d'informations |
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I (Impact Intégrité)
Integrity Impact
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High (H)
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Modification totale des données possible |
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A (Impact Disponibilité)
Availability Impact
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High (H)
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Interruption totale du service possible |