Security advisory

{
  "id": "0877f037cc4f563e9b8263a652ed7c86ae82697577ce53e7ca949a7109049811",
  "url": "https://osv.dev/vulnerability/CVE-2021-29474",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-29474",
    "summary": "HedgeDoc (formerly known as CodiMD) is an open-source collaborative markdown editor. An attacker can read arbitrary `.md` files from the server's filesystem due to an improper input validation, which results in the ability to perform a relative path traversal. To verify if you are affected, you can try to open the following URL: `http://localhost:3000/..%2F..%2FREADME#` (replace `http://localhost:3000` with your instance's base-URL e.g. `https://demo.hedgedoc.org/..%2F..%2FREADME#`). If you see a README page being rendered, you run an affected version. The attack works due the fact that the internal router passes the url-encoded alias to the `noteController.showNote`-function. This function passes the input directly to findNote() utility function, that will pass it on the the parseNoteId()-function, that tries to make sense out of the noteId/alias and check if a note already exists and if so, if a corresponding file on disk was updated. If no note exists the note creation-function is called, which pass this unvalidated alias, with a `.md` appended, into a path.join()-function which is read from the filesystem in the follow up routine and provides the pre-filled content of the new note. This allows an attacker to not only read arbitrary `.md` files from the filesystem, but also observes changes to them. The usefulness of this attack can be considered limited, since mainly markdown files are use the file-ending `.md` and all markdown files contained in the hedgedoc project, lik",
    "evidence": "osv:CVE-2021-29474",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-29474",
      "aliases": [
        "CVE-2021-29474",
        "GHSA-p528-555r-pf87"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:L/I:N/A:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/hedgedoc/hedgedoc",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "f48e36d2052bcae56081bee3c281bfc69fe7f70d"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:hedgedoc:hedgedoc:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "1.8.0"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "1.8.0-rc1",
            "1.7.2",
            "1.7.1",
            "1.7.0",
            "1.7.0-rc2",
            "1.7.0-rc1",
            "1.6.0",
            "1.5.0",
            "1.4.0",
            "1.3.2",
            "1.3.1",
            "1.3.0",
            "1.2.1",
            "1.2.0",
            "1.1.1-ce",
            "1.1.0-ce",
            "1.0.1-ce",
            "1.0.0-ce",
            "0.5.0",
            "0.4.6",
            "0.4.5",
            "0.4.4",
            "0.4.3",
            "0.4.2",
            "0.4.1",
            "0.4.0",
            "v0.3.4",
            "v0.3.3"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-29474.json"
          }
        }
      ],
      "modified": "2026-10-20T10:54:37.157170242Z",
      "provider": "osv",
      "references": [
        "https://github.com/hedgedoc/hedgedoc/security/advisories/GHSA-p528-555r-pf87"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-29474",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 385754,
  "published_at": "2021-04-26T22:15:08.9+00:00"
}