{}

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{"acknowledgement": "Red Hat would like to thank Robin \"drzobin\" Larsson for reporting this issue.", "bugzilla": {"description": "dia: dia: stack buffer overflow in Bus object via unvalidated handle count in project files", "id": "2520890", "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2520890"}, "csaw": false, "cvss3": {"cvss3_base_score": "7.8", "cvss3_scoring_vector": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H", "status": "draft"}, "cwe": "CWE-121", "details": ["A stack-based buffer overflow vulnerability exists in the Dia diagram editor when processing Network Bus objects from Dia XML project files.\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:\nbus->num_handles = attribute_num_data(attr);\nWhen a bus handle is subsequently moved, bus_handle_moved() allocates two temporary arrays on the stack:\nparallel = (real *)g_alloca(num_handles * sizeof(real));\nperp = (real *)g_alloca(num_handles * sizeof(real));\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.\nAn 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.\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.\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"], "mitigation": {"lang": "en:us", "value": "Do not open untrusted Dia project (.dia) files with Dia until a fixed version is installed. There is no configuration-based workaround."}, "name": "CVE-2026-77658", "public_date": "2026-08-21T00:00:00Z", "references": ["https://www.cve.org/CVERecord?id=CVE-2026-77658\nhttps://nvd.nist.gov/vuln/detail/CVE-2026-77658\nhttps://gitlab.gnome.org/GNOME/dia/-/blob/master/objects/network/bus.c\nhttps://gitlab.gnome.org/GNOME/dia/-/issues/581"], "statement": "A stack-based buffer overflow flaw was found in Dia. When loading a crafted Dia project file containing a Bus object with an excessive number of handles, moving a handle can cause unbounded stack allocations via g_alloca(), leading to stack exhaustion, memory corruption, and application crash. An attacker could use this flaw to crash Dia or, potentially, execute arbitrary code if a victim opens a malicious project file.", "threat_severity": "Important"}

{"affected": [{"configurations": [{"platform": null, "status": "affected", "versions": {"scheme": "semver", "value": "[0,0.98.0]"}}], "enrichment": {"confidence": 80.0, "confidence_source": "inferred", "scores": [{"score": 80.0, "source": "inferred"}, {"score": 100.0, "source": "matching"}]}, "product": "dia", "vendor": "gnome"}], "created": "2026-08-25T14:00:17.705766+00:00", "updated": "2026-08-25T14:15:05.821748+00:00", "vendors": ["gnome", "gnome$PRODUCT$dia"]}