Security advisory

{
  "id": "ddfb55329dee170dd271bef586d253100bc9ab2e60250d394513b35164e52917",
  "url": "https://osv.dev/vulnerability/CVE-2021-21321",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-21321",
    "summary": "fastify-reply-from is an npm package which is a fastify plugin to forward the current http request to another server. In fastify-reply-from before version 4.0.2, by crafting a specific URL, it is possible to escape the prefix of the proxied backend service. If the base url of the proxied server is \"/pub/\", a user expect that accessing \"/priv\" on the target service would not be possible. In affected versions, it is possible. This is fixed in version 4.0.2.",
    "evidence": "osv:CVE-2021-21321",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2021-21321",
      "aliases": [
        "CVE-2021-21321",
        "GHSA-qmw8-3v4g-gwj4"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/fastify/fastify-reply-from",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "e158d9b1dec30ba130c4db7aedb047024f8dbeea"
                },
                {
                  "fixed": "dea227dda606900cc01870d08541b4dcc69d3889"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:fastify-reply-from_project:fastify-reply-from:*:*:*:*:*:node.js:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "4.0.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "dea227dda606900cc01870d08541b4dcc69d3889"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v4.0.0",
            "v3.5.0",
            "v3.4.0",
            "v3.3.0",
            "v3.2.0",
            "v3.1.4",
            "v3.1.3",
            "v3.1.2",
            "v2.2.0",
            "v3.1.1",
            "v3.1.0",
            "v3.0.0",
            "v2.0.1",
            "v2.0.0",
            "v1.1.0",
            "v1.0.0",
            "v0.6.2",
            "v0.6.1",
            "v0.6.0",
            "v0.5.4",
            "v0.5.3",
            "v0.5.2",
            "v0.5.0",
            "v0.4.6",
            "v0.4.5",
            "v0.4.4",
            "v0.4.3",
            "v0.4.1",
            "v0.4.0",
            "v0.3.0",
            "v0.2.0",
            "v0.1.0"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-21321.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:28.526817567Z",
      "provider": "osv",
      "references": [
        "https://github.com/fastify/fastify-reply-from/security/advisories/GHSA-qmw8-3v4g-gwj4",
        "https://www.npmjs.com/package/fastify-reply-from",
        "https://github.com/fastify/fastify-reply-from/commit/dea227dda606900cc01870d08541b4dcc69d3889"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-21321",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 385419,
  "published_at": "2021-03-02T04:15:12.487+00:00"
}