FKIE_CVE-2026-107611

Vulnerability from fkie_nvd - Published: 2026-10-08 14:16 - Updated: 2026-10-08 21:10
Severity
7.1 (High) - CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H
Summary
An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server to read heap memory beyond the palette allocation and crash the viewer by sending ZRLE-encoded tiles whose palette indices exceed the declared palette size. readPaletteRleTile() and readPackedPaletteTile() use the attacker-supplied index to look up colours without validating it against the palette size; out-of-bounds heap data is copied into the framebuffer (garbled display) or the read faults, terminating the viewer.
References
33c584b5-0579-4c06-b2a0-8d8329fcab9chttps://sourceforge.net/p/vnc-tight/bugs/1657/
33c584b5-0579-4c06-b2a0-8d8329fcab9chttps://www.tightvnc.com/whatsnew.php
Impacted products
Vendor Product Version
To clipboard 

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "modules": [
            "TightVNC Viewer (ZRLE decoder)"
          ],
          "platforms": [
            "Windows"
          ],
          "product": "TightVNC",
          "programFiles": [
            "ZrleDecoder.cpp"
          ],
          "programRoutines": [
            {
              "name": "readPaletteRleTile()"
            },
            {
              "name": "readPackedPaletteTile()"
            }
          ],
          "vendor": "GlavSoft",
          "versions": [
            {
              "lessThan": "2.8.88",
              "status": "affected",
              "version": "0",
              "versionType": "custom"
            }
          ]
        }
      ],
      "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c"
    }
  ],
  "cveTags": [],
  "descriptions": [
    {
      "lang": "en",
      "value": "An out-of-bounds read vulnerability in the ZRLE decoder of GlavSoft TightVNC Viewer for Windows before 2.8.88 allows a malicious or compromised VNC server to read heap memory beyond the palette allocation and crash the viewer by sending ZRLE-encoded tiles whose palette indices exceed the declared palette size. readPaletteRleTile() and readPackedPaletteTile() use the attacker-supplied index to look up colours without validating it against the palette size; out-of-bounds heap data is copied into the framebuffer (garbled display) or the read faults, terminating the viewer."
    }
  ],
  "id": "CVE-2026-107611",
  "lastModified": "2026-10-08T21:10:00.133",
  "metrics": {
    "cvssMetricV31": [
      {
        "cvssData": {
          "attackComplexity": "LOW",
          "attackVector": "NETWORK",
          "availabilityImpact": "HIGH",
          "baseScore": 7.1,
          "baseSeverity": "HIGH",
          "confidentialityImpact": "LOW",
          "integrityImpact": "NONE",
          "privilegesRequired": "NONE",
          "scope": "UNCHANGED",
          "userInteraction": "REQUIRED",
          "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H",
          "version": "3.1"
        },
        "exploitabilityScore": 2.8,
        "impactScore": 4.2,
        "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
        "type": "Secondary"
      }
    ],
    "ssvcV203": [
      {
        "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
        "ssvcData": {
          "id": "CVE-2026-107611",
          "options": [
            {
              "exploitation": "none"
            },
            {
              "automatable": "no"
            },
            {
              "technicalImpact": "partial"
            }
          ],
          "role": "CISA Coordinator",
          "timestamp": "2026-10-08T14:02:42.563819Z",
          "version": "2.0.3"
        }
      }
    ]
  },
  "published": "2026-10-08T14:16:49.727",
  "references": [
    {
      "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
      "url": "https://sourceforge.net/p/vnc-tight/bugs/1657/"
    },
    {
      "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
      "url": "https://www.tightvnc.com/whatsnew.php"
    }
  ],
  "sourceIdentifier": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
  "vulnStatus": "Awaiting Analysis",
  "weaknesses": [
    {
      "description": [
        {
          "lang": "en",
          "value": "CWE-125"
        }
      ],
      "source": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
      "type": "Secondary"
    }
  ]
}



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