CVE-2026-34840
Hackerbay Oneuptime ≤ 10.0.42
Raw vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:NSummary
CVE-2026-34840 is a high-severity Improper Verification of Cryptographic Signature (CWE-347) vulnerability in Hackerbay Oneuptime. Its CVSS base score is 8.1 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Supply Chain Compromise (T1195); ranked at the 18th percentile by exploit likelihood (below the median); it is not currently listed in the CISA KEV catalog; a public proof-of-concept is referenced.
The strongest mitigations our analysis identified map to SC-13 (Cryptographic Protection) and SI-7 (Software, Firmware, and Information Integrity) — see the control section below for these in your framework.
Deeper analysis AI-assisted summary
Synthesised by an AI model from the NVD description and linked references — a reading aid, not an authoritative source.
CVE-2026-34840 is a high-severity vulnerability (CVSS 8.1) in the SAML SSO implementation of OneUptime, an open-source monitoring and observability platform. Affecting versions prior to 10.0.42, the flaw stems from decoupled signature verification and identity extraction in the file App/FeatureSet/Identity/Utils/SSO.ts. The isSignatureValid() function checks the first <Signature> element in the XML DOM using the xml-crypto library, while getEmail() extracts identity from the first assertion[0] via xml2js, regardless of signature position. This allows an attacker to prepend an unsigned assertion with an arbitrary identity before a valid signed assertion, enabling authentication bypass (CWE-347).
The vulnerability is exploitable over the network (AV:N) with low attack complexity (AC:L), requiring low privileges (PR:L), no user interaction (UI:N), and unchanged scope (S:U), resulting in high confidentiality and integrity impacts (C:H/I:H) but no availability disruption (A:N). A low-privileged user or attacker able to submit a crafted SAML response to OneUptime's SSO endpoint can prepend a malicious unsigned assertion containing a fabricated identity (e.g., admin email), tricking the system into authenticating them as that identity while the subsequent signed assertion passes verification.
Mitigation is available via upgrade to OneUptime version 10.0.42, where the issue was patched. Relevant resources include the security advisory at GHSA-5w5c-766x-265g, the release notes for v10.0.42, and the fixing commit 2fd7ede52f60444710628d6c1b34dee2ef9e57d1 on the project's GitHub repository.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-18533
Vulnerability Data
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…
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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.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 14 hardening rules · 5 OS baselines
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Mitigating Controls (NIST 800-53 r5) AI
Requiring cryptographic protection mechanisms forces correct signature verification to be implemented for data protection.
Mandating integrity verification tools directly requires proper cryptographic signature checking to detect unauthorized changes.
Protecting session authenticity requires correct verification of cryptographic signatures or equivalent mechanisms.
Mitigating Controls (NIST CSF 2.0) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→CSF cross-walk (authority under review) — links open the control.
Digital signatures are explicitly cited to protect integrity of data-at-rest, so proper verification directly mitigates the weakness.
Digital signatures are explicitly cited to protect integrity of data-in-transit, so proper verification directly mitigates the weakness.
Requires assessing authenticity and integrity of acquired assets, which commonly relies on signature verification but is limited to pre-acquisition.
Secure SDLC practices include code signing and signature verification requirements, addressing the weakness during development.
Mitigating Controls (ISO/IEC 27001:2022 Annex A) AI
Derived directly from the weakness types (CWEs) cited in the NVD entry via our AI-authored CWE→ISO cross-walk (authority under review) — links open the control.
Establishing approved cryptographic solutions and usage practices lowers the probability that signature-verification steps will be omitted or incorrectly implemented.
Hardening callouts derived
Configuration rules from DISA STIG baselines that bear on weaknesses of the type cited by this CVE. Each rule is shown with the relationship its mapping actually records, against the CWE it was authored against. Derived via CVE→CWE over `controls_xwalks` (authoritative rows only; rows rated `none` are excluded).
Oracle Linux 8 (2 rules)
- V-248574 YUM must be configured to prevent the installation of patches, service packs, device drivers, or OL 8 system components that have not been digitally signed using a certificate that is recognized and approved by the organization. prevents CWE-347
- V-248575 OL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-347
Oracle Linux 9 (2 rules)
- V-271525 OL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-347
- V-271523 OL 9 must check the GPG signature of locally installed software packages before installation. prevents CWE-347
RHEL 7 (2 rules)
- V-204447 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-347
- V-204448 The Red Hat Enterprise Linux operating system must prevent the installation of software, patches, service packs, device drivers, or operating system components of local packages without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-347
RHEL 8 (1 rule)
- V-230264 RHEL 8 must prevent the installation of software, patches, service packs, device drivers, or operating system components from a repository without verification they have been digitally signed using a certificate that is issued by a Certificate Authority (CA) that is recognized and approved by the organization. prevents CWE-347
RHEL 9 (1 rule)
- V-257822 RHEL 9 must have GPG signature verification enabled for all software repositories. prevents CWE-347