Vulnerability from bitnami_vulndb
Published
2026-03-27 07:10
Modified
2026-03-27 07:40
Summary
Discourse fixes loose hostname matching in spam host allowlist
Details

Discourse is an open-source discussion platform. Prior to versions 2026.3.0, 2026.2.1, and 2026.1.2, the allowed_spam_host_domains check used String#end_with? without domain boundary validation, allowing domains like attacker-example.com to bypass spam protection when example.com was allowlisted. Versions 2026.3.0, 2026.2.1, and 2026.1.2 require exact match or proper subdomain match (preceded by .) to prevent suffix-based bypass of newuser_spam_host_threshold. No known workarounds are available.

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{
  "affected": [
    {
      "package": {
        "ecosystem": "Bitnami",
        "name": "discourse",
        "purl": "pkg:bitnami/discourse"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "2026.1.0"
            },
            {
              "fixed": "2026.1.2"
            },
            {
              "introduced": "2026.2.0"
            },
            {
              "fixed": "2026.2.1"
            },
            {
              "introduced": "2026.3.0"
            },
            {
              "fixed": "2026.3.0"
            }
          ],
          "type": "SEMVER"
        }
      ],
      "severity": [
        {
          "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:N",
          "type": "CVSS_V3"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-33393"
  ],
  "database_specific": {
    "cpes": [
      "cpe:2.3:a:discourse:discourse:*:*:*:*:*:*:*:*"
    ],
    "severity": "Medium"
  },
  "details": "Discourse is an open-source discussion platform. Prior to versions 2026.3.0, 2026.2.1, and 2026.1.2, the `allowed_spam_host_domains` check used `String#end_with?` without domain boundary validation, allowing domains like `attacker-example.com` to bypass spam protection when `example.com` was allowlisted. Versions 2026.3.0, 2026.2.1, and 2026.1.2 require exact match or proper subdomain match (preceded by `.`) to prevent suffix-based bypass of `newuser_spam_host_threshold`. No known workarounds are available.",
  "id": "BIT-discourse-2026-33393",
  "modified": "2026-03-27T07:40:55.991Z",
  "published": "2026-03-27T07:10:50.748Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/discourse/discourse/commit/80b19c15fe9c7bc890d1a54f454c8446312ac6d2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/discourse/discourse/commit/d8467b9fbb3d9ed6047b4e508d3fef88a37b8a02"
    },
    {
      "type": "WEB",
      "url": "https://github.com/discourse/discourse/commit/f99099cfbc6b76fe39d6fa2daa48efd69497fb8e"
    },
    {
      "type": "WEB",
      "url": "https://github.com/discourse/discourse/security/advisories/GHSA-95r5-p6qr-hgw6"
    },
    {
      "type": "WEB",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-33393"
    }
  ],
  "schema_version": "1.6.2",
  "summary": "Discourse fixes loose hostname matching in spam host allowlist"
}


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Detection rules are retrieved from Rulezet.