SAML SSO Vulnerability in OneUptime Monitoring Platform

CVE-2026-34840

What is CVE-2026-34840?

OneUptime, an open-source monitoring and observability platform, has a significant SAML SSO issue prior to version 10.0.42. The vulnerability stems from improper handling of signature verification and identity extraction in the SSO implementation. Specifically, the method isSignatureValid() is designed to verify the first element in the XML DOM but does not prevent an attacker from injecting an unsigned assertion with a fabricated identity. This flaw allows malicious actors to bypass authentication by placing an unsigned assertion before a valid one, jeopardizing user security. The issue has been addressed in the newer version, ensuring robust protection against such attacks.

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