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.
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.003 (25.3th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 25th percentile — 25.3% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.003 · newest: 0.003 · change: +0.001
Affected products
- Hackerbay Oneuptime
- Oneuptime — versions < 10.0.42
Weakness classification (CWE)
References
- github.com/OneUptime/oneuptime/security/advisories/GHSA-5w5c-766x-265g (Exploit, Mitigation, Vendor Advisory)
- github.com/OneUptime/oneuptime/commit/2fd7ede52f60444710628d6c1b34dee2ef9e57d1 (Patch)
- github.com/OneUptime/oneuptime/releases/tag/10.0.42 (Product, 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.