CVE-2025-54572: Ruby saml Denial of Service Vulnerability

{
  "schema_version" : "1.4.0",
  "id" : "GHSA-rrqh-93c8-j966",
  "modified" : "2025-11-03T21:34:17Z",
  "published" : "2025-07-30T13:20:05Z",
  "aliases" : [ "CVE-2025-54572" ],
  "summary" : "Ruby SAML DOS vulnerability with large SAML response",
  "details" : "### Summary\nA denial-of-service vulnerability exists in ruby-saml even with the message_max_bytesize setting configured. The vulnerability occurs because the SAML response is validated for Base64 format prior to checking the message size, leading to potential resource exhaustion.\n\n### Details\n`ruby-saml` includes a `message_max_bytesize` setting intended to prevent DOS attacks and decompression bombs. However, this protection is ineffective in some cases due to the order of operations in the code:\n\nhttps://github.com/SAML-Toolkits/ruby-saml/blob/fbbedc978300deb9355a8e505849666974ef2e67/lib/onelogin/ruby-saml/saml_message.rb\n\n```ruby\n      def decode_raw_saml(saml, settings = nil)\n        return saml unless base64_encoded?(saml) # <--- Issue here. Should be moved after next code block.\n\n        settings = OneLogin::RubySaml::Settings.new if settings.nil?\n        if saml.bytesize > settings.message_max_bytesize\n          raise ValidationError.new(\"Encoded SAML Message exceeds \" + settings.message_max_bytesize.to_s + \" bytes, so was rejected\")\n        end\n\n        decoded = decode(saml)\n        ...\n      end\n```\n\nThe vulnerability is in the execution order. Prior to checking bytesize the `base64_encoded?` function performs regex matching on the entire input string:\n\n```ruby\n!!string.gsub(/[\\r\\n]|\\\\r|\\\\n|\\s/, \"\").match(BASE64_FORMAT)\n```\n\n### Impact\n_What kind of vulnerability is it? Who is impacted?_\n\nWhen successfully exploited, this vulnerability can lead to:\n\n- Excessive memory consumption\n- High CPU utilization\n- Application slowdown or unresponsiveness\n- Complete application crash in severe cases\n- Potential denial of service for legitimate users\n\nAll applications using `ruby-saml` with SAML configured and enabled are vulnerable.\n\n### Potential Solution\n\nReorder the validation steps to ensure max bytesize is checked first\n\n```ruby\ndef decode_raw_saml(saml, settings = nil)\n  settings = OneLogin::RubySaml::Settings.new if settings.nil?\n\n  if saml.bytesize > settings.message_max_bytesize\n    raise ValidationError.new(\"Encoded SAML Message exceeds \" + settings.message_max_bytesize.to_s + \" bytes, so was rejected\")\n  end\n  \n  return saml unless base64_encoded?(saml)\n  decoded = decode(saml)\n  ...\nend\n```",
  "severity" : [ {
    "type" : "CVSS_V4",
    "score" : "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "RubyGems",
      "name" : "ruby-saml"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "0"
      }, {
        "fixed" : "1.18.1"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/SAML-Toolkits/ruby-saml/security/advisories/GHSA-rrqh-93c8-j966"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2025-54572"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SAML-Toolkits/ruby-saml/pull/770"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SAML-Toolkits/ruby-saml/commit/38ef5dd1ce17514e202431f569c4f5633e6c2709"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/SAML-Toolkits/ruby-saml"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/SAML-Toolkits/ruby-saml/releases/tag/v1.18.1"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/rubysec/ruby-advisory-db/blob/master/gems/ruby-saml/CVE-2025-54572.yml"
  }, {
    "type" : "WEB",
    "url" : "https://lists.debian.org/debian-lts-announce/2025/09/msg00001.html"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400", "CWE-770" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2025-07-30T13:20:05Z",
    "nvd_published_at" : "2025-07-30T14:15:29Z"
  }
}