Security advisory

{
  "id": "0ad006ad487961b809182aae745c132d1c673277a110bb39b252cb4fb5890911",
  "url": "https://osv.dev/vulnerability/CVE-2021-43827",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-43827",
    "summary": "discourse-footnote is a library providing footnotes for posts in Discourse. ### Impact When posting an inline footnote wrapped in `` tags (e.g. `^[footnote]`, the resulting rendered HTML would include a nested ``, which is stripped by Nokogiri because it is not valid. This then caused a javascript error on topic pages because we were looking for an `` element inside the footnote reference span and getting its ID, and because it did not exist we got a null reference error in javascript. Users are advised to update to version 0.2. As a workaround editing offending posts from the rails console or the database console for self-hosters, or disabling the plugin in the admin panel can mitigate this issue.",
    "evidence": "osv:CVE-2021-43827",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2021-43827",
      "aliases": [
        "CVE-2021-43827",
        "GHSA-58vr-c56v-qr57"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/discourse/discourse-footnote",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "796617e0131277011207541313522cd1946661ab"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "range": [
                      {
                        "fixed": "796617e0131277011207541313522cd1946661ab"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-43827.json"
          }
        }
      ],
      "modified": "2026-10-20T10:55:04.910849122Z",
      "provider": "osv",
      "references": [
        "https://github.com/discourse/discourse-footnote/security/advisories/GHSA-58vr-c56v-qr57",
        "https://github.com/discourse/discourse-footnote/commit/796617e0131277011207541313522cd1946661ab"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:a:discourse:discourse_footnote:*:*:*:*:*:discourse:*:*"
            ],
            "vendor_product": "discourse:discourse_footnote",
            "extracted_events": [
              {
                "range": [
                  {
                    "fixed": "0.2"
                  }
                ],
                "source": "CPE_RANGE"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2021-43827",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 386842,
  "published_at": "2021-12-14T23:15:08.02+00:00"
}