Summary
Ruby SAML DOS vulnerability with large SAML response
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:
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)
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
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.
Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service. Typical impact: denial of service.
Affected versions
Security releases
Kodem intelligence
Severity tells you how bad this could be in the worst case. It does not tell you whether you are exposed. Exploitability and impact are functions of runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A vulnerable package can sit in your dependency tree and never run.
Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter. Kodem's runtime-powered SCA identifies whether this CVE is reachable in your applications.
Already deployed Kodem?
See it in your environmentNew to Kodem? Get a demo →Remediation advice
Kodem Kai can prioritize this vulnerability in your dependency tree and generate a fix recommendation.
Frequently Asked Questions
- What is CVE-2025-54572? CVE-2025-54572 is a medium-severity uncontrolled resource consumption vulnerability in ruby-saml (rubygems), affecting versions < 1.18.1. It is fixed in 1.18.1. Crafted input forces the application to consume excessive CPU, memory, or other resources, degrading or denying service.
- Which versions of ruby-saml are affected by CVE-2025-54572? ruby-saml (rubygems) versions < 1.18.1 is affected.
- Is there a fix for CVE-2025-54572? Yes. CVE-2025-54572 is fixed in 1.18.1. Upgrade to this version or later.
- Is CVE-2025-54572 exploitable, and should I be worried? Whether CVE-2025-54572 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
- What actually determines whether CVE-2025-54572 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
- How do I fix CVE-2025-54572? Upgrade
ruby-samlto 1.18.1 or later.