Security advisory

{
  "id": "761ac10233c4445ae875ad3d504cf1e2bab63b998590090235added313b501d4",
  "url": "https://osv.dev/vulnerability/CVE-2021-43203",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-43203",
    "summary": "In JetBrains Ktor before 1.6.4, nonce verification during the OAuth2 authentication process is implemented improperly.",
    "evidence": "osv:CVE-2021-43203",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2021-43203",
      "aliases": [
        "CVE-2021-43203"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/ktorio/ktor",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "832b70cff2522f1c6844c32fe8509a10e5a2ce4b"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:jetbrains:ktor:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.6.4"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.6.3",
            "1.6.2",
            "1.6.1",
            "1.6.0",
            "1.5.4",
            "1.5.3",
            "1.5.2",
            "1.5.1",
            "1.5.0",
            "1.4.3",
            "1.4.2",
            "1.4.1",
            "1.4.0",
            "1.3.2",
            "1.3.1",
            "1.3.0",
            "1.3.0-rc2",
            "1.3.0-rc",
            "1.3.0-beta-2",
            "1.3.0-beta-1",
            "1.2.3",
            "1.2.3-rc",
            "1.2.2",
            "1.2.1",
            "1.2.0",
            "1.2.0-rc2",
            "1.2.0-rc",
            "1.2.0-alpha-2",
            "1.2.0-alpha-1",
            "1.1.2",
            "1.1.1",
            "1.1.0",
            "1.0.1",
            "1.0.0",
            "1.0.0-rc",
            "1.0.0-beta-4",
            "1.0.0-beta-3",
            "1.0.0-beta-2",
            "1.0.0-beta-1",
            "1.0.0-alpha-3",
            "1.0.0-alpha-2",
            "1.0.0-alpha-1",
            "0.9.5",
            "0.9.4",
            "0.9.4-dev-3",
            "0.9.4-alpha-2",
            "0.9.3-alpha-4",
            "0.9.3-alpha-3",
            "0.9.3-alpha-2",
            "0.9.3-alpha-1",
            "0.9.2",
            "0.9.2-alpha-6",
            "0.9.2-alpha-5",
            "0.9.2-alpha-4",
            "0.9.2-alpha-3",
            "0.9.2-alpha-2",
            "0.9.2-alpha-1",
            "0.9.1",
            "0.9.1-alpha-10",
            "0.9.1-alpha-9",
            "0.9.1-alpha-8",
            "0.9.1-alpha-7",
            "0.9.1-alpha-6",
            "0.9.1-alpha-5",
            "0.9.1-alpha-4",
            "0.9.0",
            "0.9.0-alpha-3",
            "0.9.0-alpha-2",
            "build-0.4.1-alpha-16",
            "ktor-0.4.0",
            "build-0.4.0-alpha-15",
            "build-0.4.0-alpha-14",
            "build-0.4.0-alpha-13",
            "build-0.4.0-alpha-12",
            "build-0.4.0-alpha-11",
            "build-0.4.0-alpha-10",
            "build-0.4.0-alpha-9",
            "build-0.4.0-alpha-8",
            "build-0.4.0-alpha-7",
            "build-0.4.0-alpha-6",
            "ktor-0.3.3",
            "ktor-0.3.2",
            "ktor-0.3.1",
            "ktor-0.3.0",
            "ktor-0.2.4",
            "ktor-0.2.3",
            "ktor-0.2.2",
            "ktor-0.2.1",
            "ktor-0.2.0",
            "ktor-0.1.8",
            "ktor-0.1.7",
            "ktor-0.1.6",
            "ktor-0.1.5",
            "ktor-0.1.4",
            "ktor-0.1.3",
            "ktor-0.1.2"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-43203.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:36.232748065Z",
      "provider": "osv",
      "references": [
        "https://blog.jetbrains.com/blog/2021/11/08/jetbrains-security-bulletin-q3-2021/"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-43203",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 433920,
  "published_at": "2021-11-09T15:15:10.11+00:00"
}