Security advisory

{
  "id": "12a3e19730e6a5114c1d63b712aa4a9a9f302b59da607340093ef8f0a303239c",
  "url": "https://osv.dev/vulnerability/CVE-2018-21259",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2018-21259",
    "summary": "An issue was discovered in Mattermost Server before 4.10.1, 4.9.4, and 4.8.2. It allows attackers to cause a denial of service (application hang) via a malformed link in a channel.",
    "evidence": "osv:CVE-2018-21259",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2018-21259",
      "aliases": [
        "CVE-2018-21259"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mattermost/mattermost",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "62255442b3adea3a5a5435b982c95fa674b573cb"
                },
                {
                  "introduced": "3176e13b1f9b14192bef2337ff3fb9346f26ef66"
                },
                {
                  "fixed": "416c7523c3097af6759b7c40075df51d44624672"
                },
                {
                  "introduced": "9301e575c880970dc5642605adcc37903d176227"
                },
                {
                  "fixed": "b28fb65a4b53ee7461567e9d04fca58abe4fc054"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.8.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "4.9.0"
                      },
                      {
                        "fixed": "4.9.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "4.10.0"
                      },
                      {
                        "fixed": "4.10.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v4.10.0-rc5",
            "v4.10.0-rc4",
            "v4.10.0",
            "v4.9.1-rc1",
            "v4.9.1",
            "v4.9.0-rc6",
            "v4.9.0",
            "v4.8.1-rc1",
            "v4.8.1",
            "v4.8.0-rc6",
            "v4.8.0-rc5",
            "v4.8.0",
            "v4.8.0-rc4",
            "v4.8.0-rc3",
            "v4.8.0-rc2",
            "v4.8.0-rc1",
            "v4.7.0-rc1",
            "v4.6.0-rc2",
            "v4.6.0-rc1",
            "v4.5.0-rc1",
            "v4.4.0-rc1",
            "v4.3.0-rc1",
            "v4.2.0-rc1",
            "v0.5.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2018-21259.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:36.428820181Z",
      "provider": "osv",
      "references": [
        "https://mattermost.com/security-updates/"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2018-21259",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 433970,
  "published_at": "2020-06-19T17:15:12.85+00:00"
}