Security advisory

{
  "id": "7a793aaaf4845b9589d5cad2a43c18c7835c544424d4bd7d8572d4e428eab829",
  "url": "https://osv.dev/vulnerability/CVE-2018-20021",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2018-20021",
    "summary": "LibVNC before commit c3115350eb8bb635d0fdb4dbbb0d0541f38ed19c contains a CWE-835: Infinite loop vulnerability in VNC client code. Vulnerability allows attacker to consume excessive amount of resources like CPU and RAM",
    "evidence": "osv:CVE-2018-20021",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2018-20021",
      "aliases": [
        "CVE-2018-20021"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/libvnc/libvncserver",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "0a70095271d845d16a3ed17354841b01f33963ad"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:libvnc_project:libvncserver:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.9.12"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "LibVNCServer-0.9.11",
            "LibVNCServer-0.9.10",
            "LibVNCServer-0.9.9",
            "LibVNCServer-0.9.8",
            "X11VNC_0_9_12",
            "X11VNC_0_9_11",
            "X11VNC_0_9_10",
            "X11VNC_0_9_9",
            "X11VNC_0_9_8",
            "X11VNC_0_9_7",
            "X11VNC_REL_0_9_6",
            "X11VNC_REL_0_9_5",
            "X11VNC_REL_0_9_4"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-20021.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:26.140229861Z",
      "provider": "osv",
      "references": [
        "https://lists.debian.org/debian-lts-announce/2019/10/msg00042.html",
        "https://lists.debian.org/debian-lts-announce/2019/11/msg00033.html",
        "https://lists.debian.org/debian-lts-announce/2019/12/msg00028.html",
        "https://usn.ubuntu.com/4547-1/",
        "https://usn.ubuntu.com/4547-2/",
        "https://usn.ubuntu.com/4587-1/",
        "https://ics-cert.kaspersky.com/advisories/klcert-advisories/2018/12/19/klcert-18-031-libvnc-infinite-loop/",
        "https://lists.debian.org/debian-lts-announce/2018/12/msg00017.html",
        "https://security.gentoo.org/glsa/201908-05",
        "https://security.gentoo.org/glsa/202006-06",
        "https://usn.ubuntu.com/3877-1/",
        "https://www.debian.org/security/2019/dsa-4383"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:canonical:ubuntu_linux:14.04:*:*:*:lts:*:*:*",
              "cpe:2.3:o:canonical:ubuntu_linux:16.04:*:*:*:lts:*:*:*",
              "cpe:2.3:o:canonical:ubuntu_linux:18.04:*:*:*:lts:*:*:*",
              "cpe:2.3:o:canonical:ubuntu_linux:18.10:*:*:*:*:*:*:*"
            ],
            "vendor_product": "canonical:ubuntu_linux",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "14.04"
                  },
                  {
                    "last_affected": "14.04"
                  },
                  {
                    "introduced": "16.04"
                  },
                  {
                    "last_affected": "16.04"
                  },
                  {
                    "introduced": "18.04"
                  },
                  {
                    "last_affected": "18.04"
                  },
                  {
                    "introduced": "18.10"
                  },
                  {
                    "last_affected": "18.10"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          },
          {
            "cpes": [
              "cpe:2.3:o:debian:debian_linux:8.0:*:*:*:*:*:*:*",
              "cpe:2.3:o:debian:debian_linux:9.0:*:*:*:*:*:*:*"
            ],
            "vendor_product": "debian:debian_linux",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "8.0"
                  },
                  {
                    "last_affected": "8.0"
                  },
                  {
                    "introduced": "9.0"
                  },
                  {
                    "last_affected": "9.0"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2018-20021",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 431546,
  "published_at": "2018-12-19T16:29:00.42+00:00"
}