Security advisory

{
  "id": "cb9b16f06a0782088e14a76249d91fa6f93e6956c6c5a3e906bc8c633f8bbcf5",
  "url": "https://osv.dev/vulnerability/CVE-2021-4138",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-4138",
    "summary": "Improved Host header checks to reject requests not sent to a well-known local hostname or IP, or the server-specified hostname.",
    "evidence": "osv:CVE-2021-4138",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-4138",
      "aliases": [
        "CVE-2021-4138"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/mozilla/geckodriver",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "d06ed1be13ef77e4f75ef06beb6ab829e2eef191"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:mozilla:geckodriver:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "0.30.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "d06ed1be13ef77e4f75ef06beb6ab829e2eef191"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v0.30.0"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v0.29.1",
            "v0.29.0",
            "v0.28.0",
            "v0.27.0",
            "v0.25.0",
            "v0.24.0",
            "v0.23.0",
            "v0.22.0",
            "v0.21.0",
            "v0.20.1",
            "v0.20.0",
            "v0.19.1",
            "v0.19.0",
            "v0.18.0",
            "v0.17.0",
            "v0.16.1",
            "v0.16.0",
            "v0.15.0",
            "v0.14.0",
            "v0.13.0",
            "v0.12.0",
            "v0.11.1",
            "v0.11.0",
            "v0.10.0",
            "v0.9.0",
            "v0.8.0",
            "v0.7.1",
            "v0.6.2",
            "v0.6.0",
            "v0.5.0",
            "v0.4.2",
            "v0.4.1",
            "v0.4.0",
            "0.3.0",
            "v0.2.0",
            "v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-4138.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:58.388122636Z",
      "provider": "osv",
      "references": [
        "https://github.com/mozilla/geckodriver/releases/tag/v0.30.0",
        "https://bugzilla.mozilla.org/show_bug.cgi?id=1652612"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-4138",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 386597,
  "published_at": "2022-05-02T23:15:08.057+00:00"
}