Ruby SAML Library Denial-of-Service Vulnerability

A denial-of-service vulnerability has been identified in the Ruby SAML library, specifically in versions prior to 1.18.1. The issue arises because the library validates SAML responses for Base64 encoding before checking the message size, creating a risk of resource exhaustion. This vulnerability exists even when the 'message_max_bytesize' setting is configured, as the protection is ineffective in certain scenarios due to the order of operations in the code.

Impact

Exploitation of this vulnerability can lead to excessive memory usage, increased CPU load, application slowdowns or unresponsiveness, and in severe cases, complete application crashes. This can also cause denial-of-service conditions for legitimate users.

Remediation

Users can upgrade to Ruby SAML version 1.18.1 or later to address this vulnerability.