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

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.

Scores

EPSS (exploitation in 30 days)

0.27% · top 81% of all CVEs (5 Nov 2026)

CISA SSVC

Exploitation: poc · Automatable: no · Technical impact: total

The list uses the assigner's score when there is one, then CISA's, then NVD's: High 8.1.

Weakness

• CWE-347: Improper Verification of Cryptographic Signature (opens in a new tab)All about CWE-347 and its CVEs

Affected products

• OneUptime · oneuptime

  • affected < 10.0.42

References (3)

• https://github.com/OneUptime/oneuptime/security/advisories/GHSA-5w5c-766x-265g (opens in a new tab)x_refsource_CONFIRM
• https://github.com/OneUptime/oneuptime/commit/2fd7ede52f60444710628d6c1b34dee2ef9e57d1 (opens in a new tab)x_refsource_MISC
• https://github.com/OneUptime/oneuptime/releases/tag/10.0.42 (opens in a new tab)x_refsource_MISC

Sources

The same CVE in the primary databases and aggregators, to check against.

• CVE.org record (opens in a new tab)
• CVE List JSON (GitHub) (opens in a new tab)
• NVD (opens in a new tab)
• FIRST EPSS (opens in a new tab)
• OSV.dev (opens in a new tab)
• GitHub Advisories (opens in a new tab)
• CIRCL Vulnerability-Lookup (opens in a new tab)

Badge for a README or a ticket

[![CVE-2026-34840](https://trackcve.app/badge/CVE-2026-34840.svg)](https://trackcve.app/cve/CVE-2026-34840)

Record last updated 2 Apr 2026, 20:20 UTC.