What’s Vulnerable › Vulnerabilities

CVE-2026-34840: OneUptime SSO: Multi-Assertion Identity Injection via Decoupled Signature Verification

• Severity: high (CVSS 8.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.3% probability of exploitation in the next 30 days
• Public exploit or detection template: yes
• Published: 2026-04-02 · updated 2026-10-06
• Weakness: CWE-347

Description

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

• oneuptime: before 10.0.42 — fixed in 10.0.42

How to fix

Upgrade to a fixed version: oneuptime 10.0.42. Check the vendor advisory for mitigations.

References

• https://github.com/OneUptime/oneuptime/commit/2fd7ede52f60444710628d6c1b34dee2ef9e57d1
• https://github.com/OneUptime/oneuptime/releases/tag/10.0.42
• https://github.com/OneUptime/oneuptime/security/advisories/GHSA-5w5c-766x-265g

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