{
  "affected": [
    {
      "ranges": [
        {
          "database_specific": {
            "extracted_events": [
              {
                "introduced": "0"
              },
              {
                "fixed": "2026.1.6"
              },
              {
                "introduced": "2026.5.0-latest"
              },
              {
                "fixed": "2026.5.2"
              },
              {
                "introduced": "2026.6.0-latest"
              },
              {
                "fixed": "2026.6.1"
              },
              {
                "introduced": "2026.7.0-latest"
              },
              {
                "fixed": "2026.7.0"
              }
            ],
            "source": [
              "AFFECTED_FIELD",
              "REFERENCES"
            ]
          },
          "events": [
            {
              "introduced": "0"
            },
            {
              "introduced": "640840d818f4ee9375829ece0ef452923bb0c012"
            },
            {
              "introduced": "06d03da34c4ed09ea59f917f045ba250d2b6320d"
            },
            {
              "introduced": "ded677e00beb0e9bae6e70b69582aecfb72b5477"
            },
            {
              "fixed": "94190ccb5176eb4ab1f2b509fcecc3fc682dadae"
            },
            {
              "fixed": "3a87be49d621faddf5cea3f6a090adc9b7cbb7e8"
            },
            {
              "fixed": "b6419ddb26f109092cdc5fdc4b2624fe95a5e8d4"
            },
            {
              "fixed": "ded677e00beb0e9bae6e70b69582aecfb72b5477"
            },
            {
              "fixed": "a3e10759fef47f03d450649bb51d9e84f4c68b8f"
            },
            {
              "fixed": "c2eb6b0e5597d6f28f4be739b83300bc9c69e3cd"
            },
            {
              "fixed": "caa615c371b1696982ee11ac8f3558f0f8ced584"
            },
            {
              "fixed": "f503971d311b7b0dfdb751ee8cfd67e8cb99f5c5"
            }
          ],
          "repo": "https://github.com/discourse/discourse",
          "type": "GIT"
        }
      ]
    }
  ],
  "aliases": [
    "GHSA-3x7x-24rq-h5j6"
  ],
  "database_specific": {
    "cna_assigner": "GitHub_M",
    "cwe_ids": [
      "CWE-178"
    ],
    "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72721.json"
  },
  "details": "Discourse is an open-source discussion platform. Prior to 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0, Onebox::DomainChecker.is_blocked? compares hostnames and SiteSetting.blocked_onebox_domains entries case-sensitively, allowing an attacker to bypass configured Onebox domain restrictions by changing character casing in a redirect target hostname. This issue is fixed in versions 2026.1.6, 2026.5.2, 2026.6.1, and 2026.7.0.",
  "id": "CVE-2026-72721",
  "modified": "2026-09-10T03:31:06.837843863Z",
  "published": "2026-08-10T15:48:30.548Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/72xxx/CVE-2026-72721.json"
    },
    {
      "type": "ADVISORY",
      "url": "https://github.com/discourse/discourse/security/advisories/GHSA-3x7x-24rq-h5j6"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-72721"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/commit/a3e10759fef47f03d450649bb51d9e84f4c68b8f"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/commit/c2eb6b0e5597d6f28f4be739b83300bc9c69e3cd"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/commit/caa615c371b1696982ee11ac8f3558f0f8ced584"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/commit/f503971d311b7b0dfdb751ee8cfd67e8cb99f5c5"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/pull/42091"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/pull/42092"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/pull/42093"
    },
    {
      "type": "FIX",
      "url": "https://github.com/discourse/discourse/pull/42094"
    }
  ],
  "schema_version": "1.9.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    }
  ],
  "summary": "Discourse: Onebox Domain Blocklist Bypass via Case-Sensitive Comparison"
}