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How the CVE Works
The vulnerability in ruby-saml arises from improper validation order when processing SAML responses. The library first checks if the input is Base64-encoded using a regex pattern (!!string.gsub(/[\r\n]|\\r|\\n|\s/, "").match(BASE64_FORMAT) before verifying the message size via message_max_bytesize. Attackers can exploit this by sending excessively large payloads, forcing the application to perform costly regex operations, leading to CPU/memory exhaustion and denial-of-service.
DailyCVE Form
Platform: Ruby-SAML
Version: < 1.15.0
Vulnerability: DoS via regex
Severity: Critical
Date: 2023-08-15
Prediction: Patch by 2023-09-10
What Undercode Say
git clone https://github.com/SAML-Toolkits/ruby-saml cd ruby-saml grep -r "base64_encoded?" lib/
PoC: Malformed large SAML payload payload = "A" 10_000_000 response = OneLogin::RubySaml::Response.new(payload)
How Exploit
- Craft oversized SAML response
- Bypass `message_max_bytesize` check
- Trigger CPU/memory exhaustion
Protection from this CVE
- Update to >= 1.15.0
- Reorder validation logic
Impact
- Service disruption
- Resource starvation
- Application crashes
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Reported By: github.com
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