FKIE_CVE-2026-77658

Vulnerability from fkie_nvd - Published: 2026-08-26 13:19 - Updated: 2026-08-26 14:17
Severity
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
Summary
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
References
patrick@puiterwijk.orghttps://access.redhat.com/security/cve/CVE-2026-77658
patrick@puiterwijk.orghttps://bugzilla.redhat.com/show_bug.cgi?id=2520890
patrick@puiterwijk.orghttps://gitlab.gnome.org/GNOME/dia/-/blob/master/objects/network/bus.c
patrick@puiterwijk.orghttps://gitlab.gnome.org/GNOME/dia/-/issues/581
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "collectionURL": "https://gitlab.gnome.org/GNOME/dia/-/issues/581",
          "defaultStatus": "unaffected",
          "packageName": "dia",
          "product": "Dia",
          "vendor": "GNOME",
          "versions": [
            {
              "lessThanOrEqual": "0.98.0",
              "status": "affected",
              "version": "0",
              "versionType": "semver"
            }
          ]
        }
      ],
      "source": "patrick@puiterwijk.org"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "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-\u003enum_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. 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"
    }
  ],
  "id": "CVE-2026-77658",
  "lastModified": "2026-08-26T14:17:15.490",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "LOCAL",
          "availabilityImpact": "HIGH",
          "baseScore": 7.8,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "HIGH",
          "integrityImpact": "HIGH",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 1.8,
        "impactScore": 5.9,
        "source": "patrick@puiterwijk.org",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-77658",
          "options": [
            {
              "exploitation": "poc"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "total"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-08-26T13:09:44.563034Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-08-26T13:19:22.043",
  "references": [
    {
      "source": "patrick@puiterwijk.org",
      "url": "https://access.redhat.com/security/cve/CVE-2026-77658"
    },
    {
      "source": "patrick@puiterwijk.org",
      "url": "https://bugzilla.redhat.com/show_bug.cgi?id=2520890"
    },
    {
      "source": "patrick@puiterwijk.org",
      "url": "https://gitlab.gnome.org/GNOME/dia/-/blob/master/objects/network/bus.c"
    },
    {
      "source": "patrick@puiterwijk.org",
      "url": "https://gitlab.gnome.org/GNOME/dia/-/issues/581"
    }
  ],
  "sourceIdentifier": "patrick@puiterwijk.org",
  "vulnStatus": "Received",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-121"
        }
      ],
      "source": "patrick@puiterwijk.org",
      "type": "Secondary"
    }
  ]
}



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