Discourse: Hidden group names and access metadata are exposed to moderators through the `category-chatables` endpoint

{
  "id": "672e1968055afbcfd98328015b6a60119f67b4be633c0d4110b9b2e356fcb0b7",
  "url": "https://osv.dev/vulnerability/CVE-2026-33300",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "Discourse: Hidden group names and access metadata are exposed to moderators through the `category-chatables` endpoint",
    "summary": "Discourse is an open-source discussion platform. From versions 2026.1.0-latest to before 2026.1.3, 2026.2.0-latest to before 2026.2.2, and 2026.3.0-latest to before 2026.3.0, an authorization bypass in the Category Chatables Controller show action allowed moderators to get information on hidden groups names and user count. This issue has been patched in versions 2026.1.3, 2026.2.2, and 2026.3.0.",
    "evidence": "osv:CVE-2026-33300",
    "products": [],
    "severity": "medium",
    "structured": {
      "id": "CVE-2026-33300",
      "aliases": [
        "BIT-discourse-2026-33300",
        "CVE-2026-33300",
        "GHSA-wrwm-vqx2-6x4v"
      ],
      "metrics": [
        {
          "type": "CVSS_V4",
          "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/discourse/discourse",
              "type": "GIT",
              "events": [
                {
                  "introduced": "322d3c0ac6a8f133b3f82875e9dbbe310f638c1b"
                },
                {
                  "fixed": "b3f024ce9587e678216892cbd967201b2450e197"
                },
                {
                  "introduced": "f7cec86997edc21d6074ceb7666f7e2e6e1b1fdf"
                },
                {
                  "fixed": "4431801e7b5af883edb430643fdace7608ffb6fb"
                },
                {
                  "introduced": "896e810e1b296478bba91559a8fc89a9926f11fe"
                },
                {
                  "fixed": "07f66658cce81a099a0d7115db5f3c69f5d3cca2"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:discourse:discourse:*:*:*:*:latest:*:*:*",
                    "range": [
                      {
                        "introduced": "2026.1.0"
                      },
                      {
                        "fixed": "2026.1.3"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:discourse:discourse:*:*:*:*:latest:*:*:*",
                    "range": [
                      {
                        "introduced": "2026.2.0"
                      },
                      {
                        "fixed": "2026.2.2"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "cpe": "cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest:*:*:*",
                    "range": [
                      {
                        "introduced": "2026.3.0"
                      },
                      {
                        "last_affected": "2026.3.0"
                      }
                    ],
                    "source": "CPE_STRING"
                  },
                  {
                    "cpe": "cpe:2.3:a:discourse:discourse:2026.3.0:*:*:*:latest.1:*:*:*",
                    "range": [
                      {
                        "introduced": "2026.3.0"
                      },
                      {
                        "last_affected": "2026.3.0"
                      }
                    ],
                    "source": "CPE_STRING"
                  },
                  {
                    "range": [
                      {
                        "fixed": "07f66658cce81a099a0d7115db5f3c69f5d3cca2"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  }
                ]
              }
            }
          ],
          "versions": [
            "2026.3.0",
            "v2026.1.2",
            "v2026.2.1",
            "v2026.3.0-latest.1",
            "v2026.1.1",
            "v2026.2.0",
            "v2026.3.0-latest",
            "v2026.1.0",
            "stable",
            "esr",
            "v2026.2.0-latest",
            "v2026.1.0-latest"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-33300.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:50.267566108Z",
      "provider": "osv",
      "references": [
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33300.json",
        "https://github.com/discourse/discourse/security/advisories/GHSA-wrwm-vqx2-6x4v",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-33300",
        "https://github.com/discourse/discourse/commit/07f66658cce81a099a0d7115db5f3c69f5d3cca2"
      ],
      "provider_metadata": {
        "cwe_ids": [
          "CWE-200"
        ],
        "cna_assigner": "GitHub_M",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/33xxx/CVE-2026-33300.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2026-33300",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 518778,
  "published_at": "2026-03-31T17:42:00.882+00:00"
}