CVE-2026-107611 (GCVE-0-2026-107611)

Vulnerability from cvelistv5 – Published: 2026-10-08 13:39 – Updated: 2026-10-08 14:03
VLAI
Title
Out-of-bounds read in TightVNC Viewer ZRLE palette decoding
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.
Severity
7.1 (High)
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H
SSVC
Exploitation: none Automatable: no Technical Impact: partial
CISA Coordinator · CISA-ADP (v2.0.3)
Decision recorded 2026-10-08 14:02 UTC
CWE
Assigner
securin CNA under the mitre root
CNA scorecard B 80/100 over 71 records in the last 180 days details
References
Impacted products
Vendor Product Version CPE status
GlavSoft TightVNC Affected: 0 , < 2.8.88 (custom)
guessed Create a notification for this product.
Credits
Arjun Basnet from Securin
Show details on NVD website
To clipboard 

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-107611",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "no"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-10-08T14:02:42.563819Z",
                "version": "2.0.3"
              },
              "type": "ssvc"
            }
          }
        ],
        "providerMetadata": {
          "dateUpdated": "2026-10-08T14:03:01.404Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "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"
            }
          ]
        }
      ],
      "credits": [
        {
          "lang": "en",
          "type": "finder",
          "value": "Arjun Basnet from Securin"
        }
      ],
      "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."
        }
      ],
      "impacts": [
        {
          "capecId": "CAPEC-540",
          "descriptions": [
            {
              "lang": "en",
              "value": "CAPEC-540 Overread Buffers"
            }
          ]
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.1,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H",
            "version": "3.1"
          },
          "format": "CVSS",
          "scenarios": [
            {
              "lang": "en",
              "value": "GENERAL"
            }
          ]
        }
      ],
      "problemTypes": [
        {
          "descriptions": [
            {
              "cweId": "CWE-125",
              "description": "CWE-125 Out-of-bounds Read",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-08T13:39:48.883Z",
        "orgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
        "shortName": "securin"
      },
      "references": [
        {
          "name": "TightVNC bug #1657",
          "tags": [
            "issue-tracking"
          ],
          "url": "https://sourceforge.net/p/vnc-tight/bugs/1657/"
        },
        {
          "name": "TightVNC release notes (2.8.88)",
          "tags": [
            "release-notes",
            "patch"
          ],
          "url": "https://www.tightvnc.com/whatsnew.php"
        }
      ],
      "solutions": [
        {
          "lang": "en",
          "value": "Upgrade TightVNC for Windows to version 2.8.88 or later."
        }
      ],
      "source": {
        "discovery": "EXTERNAL"
      },
      "timeline": [
        {
          "lang": "en",
          "time": "2026-05-30T00:00:00.000Z",
          "value": "Reported to GlavSoft"
        },
        {
          "lang": "en",
          "time": "2026-06-02T00:00:00.000Z",
          "value": "Vendor acknowledged"
        },
        {
          "lang": "en",
          "time": "2026-06-19T00:00:00.000Z",
          "value": "TightVNC 2.8.88 released with fix"
        }
      ],
      "title": "Out-of-bounds read in TightVNC Viewer ZRLE palette decoding",
      "workarounds": [
        {
          "lang": "en",
          "value": "Connect only to trusted VNC servers until the viewer is upgraded."
        }
      ]
    }
  },
  "cveMetadata": {
    "assignerOrgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
    "assignerShortName": "securin",
    "cveId": "CVE-2026-107611",
    "datePublished": "2026-10-08T13:39:48.883Z",
    "dateReserved": "2026-10-08T13:23:07.677Z",
    "dateUpdated": "2026-10-08T14:03:01.404Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2",
  "vulnerability-lookup:meta": {
    "epss": {
      "cve": "CVE-2026-107611",
      "date": "2026-10-16",
      "epss": "0.00235",
      "percentile": "0.13492"
    },
    "nvd": {
      "cve": {
        "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"
          }
        ]
      }
    },
    "vulnrichment": {
      "containers": {
        "adp": [
          {
            "metrics": [
              {
                "other": {
                  "content": {
                    "id": "CVE-2026-107611",
                    "options": [
                      {
                        "Exploitation": "none"
                      },
                      {
                        "Automatable": "no"
                      },
                      {
                        "Technical Impact": "partial"
                      }
                    ],
                    "role": "CISA Coordinator",
                    "timestamp": "2026-10-08T14:02:42.563819Z",
                    "version": "2.0.3"
                  },
                  "type": "ssvc"
                }
              }
            ],
            "providerMetadata": {
              "dateUpdated": "2026-10-08T14:02:57.754Z",
              "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
              "shortName": "CISA-ADP"
            },
            "title": "CISA ADP Vulnrichment"
          }
        ],
        "cna": {
          "affected": [
            {
              "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"
                }
              ]
            }
          ],
          "credits": [
            {
              "lang": "en",
              "type": "finder",
              "value": "Arjun Basnet from Securin"
            }
          ],
          "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."
            }
          ],
          "impacts": [
            {
              "capecId": "CAPEC-540",
              "descriptions": [
                {
                  "lang": "en",
                  "value": "CAPEC-540 Overread Buffers"
                }
              ]
            }
          ],
          "metrics": [
            {
              "cvssV3_1": {
                "baseScore": 7.1,
                "baseSeverity": "HIGH",
                "vectorString": "CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:L/I:N/A:H",
                "version": "3.1"
              },
              "format": "CVSS",
              "scenarios": [
                {
                  "lang": "en",
                  "value": "GENERAL"
                }
              ]
            }
          ],
          "problemTypes": [
            {
              "descriptions": [
                {
                  "cweId": "CWE-125",
                  "description": "CWE-125 Out-of-bounds Read",
                  "lang": "en",
                  "type": "CWE"
                }
              ]
            }
          ],
          "providerMetadata": {
            "dateUpdated": "2026-10-08T13:39:48.883Z",
            "orgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
            "shortName": "securin"
          },
          "references": [
            {
              "name": "TightVNC bug #1657",
              "tags": [
                "issue-tracking"
              ],
              "url": "https://sourceforge.net/p/vnc-tight/bugs/1657/"
            },
            {
              "name": "TightVNC release notes (2.8.88)",
              "tags": [
                "release-notes",
                "patch"
              ],
              "url": "https://www.tightvnc.com/whatsnew.php"
            }
          ],
          "solutions": [
            {
              "lang": "en",
              "value": "Upgrade TightVNC for Windows to version 2.8.88 or later."
            }
          ],
          "source": {
            "discovery": "EXTERNAL"
          },
          "timeline": [
            {
              "lang": "en",
              "time": "2026-05-30T00:00:00.000Z",
              "value": "Reported to GlavSoft"
            },
            {
              "lang": "en",
              "time": "2026-06-02T00:00:00.000Z",
              "value": "Vendor acknowledged"
            },
            {
              "lang": "en",
              "time": "2026-06-19T00:00:00.000Z",
              "value": "TightVNC 2.8.88 released with fix"
            }
          ],
          "title": "Out-of-bounds read in TightVNC Viewer ZRLE palette decoding",
          "workarounds": [
            {
              "lang": "en",
              "value": "Connect only to trusted VNC servers until the viewer is upgraded."
            }
          ]
        }
      },
      "cveMetadata": {
        "assignerOrgId": "33c584b5-0579-4c06-b2a0-8d8329fcab9c",
        "assignerShortName": "securin",
        "cveId": "CVE-2026-107611",
        "datePublished": "2026-10-08T13:39:48.883Z",
        "dateReserved": "2026-10-08T13:23:07.677Z",
        "dateUpdated": "2026-10-08T14:03:01.404Z",
        "state": "PUBLISHED"
      },
      "dataType": "CVE_RECORD",
      "dataVersion": "5.2"
    }
  }
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.




Drag nodes to arrange them. Double-click a related vulnerability to open it, or a source to visit its link. The Physics button on the left tunes the layout and the simulation; the legend at the bottom left hides or shows nodes by kind and by sighting type.

Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.
Vulnerability timeline

Sightings and recorded dates, grouped by day · UTC

JSON

Loading timeline…




    Related by attack behaviour

    Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.