CVE-2026-34840

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

HIGH
8.1
CVSS Score
Published: April 2, 2026 at 06:52 PM UTC
Updated: October 6, 2026 at 10:10 PM UTC
2 products affected across 2 vendorsOneuptimeOneUptime

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Severity
HIGH8.1
Exploit prediction
EPSS 0.3%
SSVC
PoC

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

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

v < 10.0.42
Affected range stops below 10.0.42, so it looks safe — our inference, not a vendor statement
v < 10.0.42
Affected range stops below 10.0.42, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

References (3)

x_refsource_CONFIRMExploitMitigationVendor Advisory
Source: cverecord
https://github.com/OneUptime/oneuptime/security/advisories/GHSA-5w5c-766x-265g
x_refsource_MISCProductRelease Notes
Source: cverecord
https://github.com/OneUptime/oneuptime/releases/tag/10.0.42

SSVC — Action Prioritization

SSVCPoCNot automatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

8.1HIGHGitHub_M
Attack Vector
NETWORK
Complexity
LOW
Privileges
LOW
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-347

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