CVE-2026-34840: Hackerbay Oneuptime

High severity, CVSS 8.1. EPSS: 0.3% chance of exploitation in the next 30 days.

OneUptime is an open-source monitoring and observability platform. Prior to version 10.0.42, OneUptime's SAML SSO implementation (App/FeatureSet/Identity/Utils/SSO.ts) has decoupled signature verification and identity extraction. isSignatureValid() verifies the first <Signature> element in the XML DOM using xml-crypto, while getEmail() always reads from assertion[0] via xml2js. An attacker can prepend an unsigned assertion containing an arbitrary identity before a legitimately signed assertion, resulting in authentication bypass. This issue has been patched in version 10.0.42.

Affected products

• Hackerbay Oneuptime: before 10.0.42 (fixed in 10.0.42)

Published 2026-04-02. Last modified 2026-10-06.