GHSA-RRQH-93C8-J966

Vulnerability from github – Published: 2025-07-30 13:20 – Updated: 2025-11-03 21:34
VLAI
Summary
Ruby SAML DOS vulnerability with large SAML response
Details

Summary

A 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.

Details

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:

https://github.com/SAML-Toolkits/ruby-saml/blob/fbbedc978300deb9355a8e505849666974ef2e67/lib/onelogin/ruby-saml/saml_message.rb

      def decode_raw_saml(saml, settings = nil)
        return saml unless base64_encoded?(saml) # <--- Issue here. Should be moved after next code block.

        settings = OneLogin::RubySaml::Settings.new if settings.nil?
        if saml.bytesize > settings.message_max_bytesize
          raise ValidationError.new("Encoded SAML Message exceeds " + settings.message_max_bytesize.to_s + " bytes, so was rejected")
        end

        decoded = decode(saml)
        ...
      end

The vulnerability is in the execution order. Prior to checking bytesize the base64_encoded? function performs regex matching on the entire input string:

!!string.gsub(/[\r\n]|\\r|\\n|\s/, "").match(BASE64_FORMAT)

Impact

What kind of vulnerability is it? Who is impacted?

When successfully exploited, this vulnerability can lead to:

  • Excessive memory consumption
  • High CPU utilization
  • Application slowdown or unresponsiveness
  • Complete application crash in severe cases
  • Potential denial of service for legitimate users

All applications using ruby-saml with SAML configured and enabled are vulnerable.

Potential Solution

Reorder the validation steps to ensure max bytesize is checked first

def decode_raw_saml(saml, settings = nil)
  settings = OneLogin::RubySaml::Settings.new if settings.nil?

  if saml.bytesize > settings.message_max_bytesize
    raise ValidationError.new("Encoded SAML Message exceeds " + settings.message_max_bytesize.to_s + " bytes, so was rejected")
  end

  return saml unless base64_encoded?(saml)
  decoded = decode(saml)
  ...
end
Severity
6.9 (Medium)
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
Show details on source website
To clipboard 

{
  "affected": [
    {
      "package": {
        "ecosystem": "RubyGems",
        "name": "ruby-saml"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.18.1"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2025-54572"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-400",
      "CWE-770"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2025-07-30T13:20:05Z",
    "nvd_published_at": "2025-07-30T14:15:29Z",
    "severity": "MODERATE"
  },
  "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) # \u003c--- Issue here. Should be moved after next code block.\n\n        settings = OneLogin::RubySaml::Settings.new if settings.nil?\n        if saml.bytesize \u003e 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 \u003e 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```",
  "id": "GHSA-rrqh-93c8-j966",
  "modified": "2025-11-03T21:34:17Z",
  "published": "2025-07-30T13:20:05Z",
  "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"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "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",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Ruby SAML DOS vulnerability with large SAML response"
}



Log in or create an account to share your comment.




Tags
Taxonomy of the tags.





Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

Author Source Type Date Other

Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.



Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.