Vulnerability in Hackerbay Oneuptime
CVE-2026-34840
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.
EPSS: 0.003 (18.2th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 8.1 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N.
Affected products
- Hackerbay Oneuptime
- Oneuptime — versions < 10.0.42
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Exploit, Mitigation, Vendor Advisory)
- security-advisories@github.com (Patch, x_refsource_MISC)
- security-advisories@github.com (Product, x_refsource_MISC, Release Notes)
Frequently asked questions
- What is CVE-2026-34840?
- CVE-2026-34840 is a high-severity vulnerability in Hackerbay Oneuptime, classified under Improper Verification of Cryptographic Signature. CVSS score: 8.1/10. Published 2026-04-02.
- How severe is CVE-2026-34840?
- High severity. CVSS v3 base score is 8.1 out of 10.