Raw vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:NSummary
CVE-2026-28787 is a high-severity Improper Authentication (CWE-287) vulnerability in Hackerbay Oneuptime. Its CVSS base score is 8.2 (High).
Operationally, exploitation aligns with the MITRE ATT&CK technique Network Sniffing (T1040); ranked at the 20th 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 IA-2 (Identification and Authentication (Organizational Users)) and IA-3 (Device Identification and Authentication) — 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-2026-28787 affects OneUptime, an open-source solution for monitoring and managing online services, specifically in versions 10.0.11 and prior. The vulnerability resides in the WebAuthn authentication implementation, which fails to store the authentication challenge on the server side. Instead, it returns the challenge to the client and accepts it back from the client request body during verification. This design violates the WebAuthn specification (W3C Web Authentication Level 2, §13.4.3) and enables replay attacks on valid WebAuthn assertions. The issue is associated with CWE-287 (Improper Authentication) and CWE-294 (Authentication Bypass by Capture-replay), with a CVSS v3.1 base score of 8.2 (AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N).
An attacker with low privileges (PR:L) can exploit this over the network (AV:N), though it requires high attack complexity (AC:H) and involves a scope change (S:C). Exploitation begins with obtaining a valid WebAuthn assertion through means such as cross-site scripting (XSS), man-in-the-middle (MitM) interception, or exposure via logs. The attacker can then replay this assertion indefinitely during authentication attempts, completely bypassing second-factor authentication without user interaction (UI:N). Successful exploitation grants high confidentiality and integrity impacts (C:H/I:H), potentially allowing unauthorized access to protected resources.
The GitHub Security Advisory (GHSA-gjjc-pcwp-c74m) details the issue but notes that no known patches are available for affected versions of OneUptime. Security practitioners should monitor for updates from the OneUptime project and consider alternative authentication mechanisms or network controls to mitigate replay risks in the interim.
OWASP Top 10 for Web (2025)
EU & UK References
- 🇪🇺 ENISA EUVD: EUVD-2026-9996
Vulnerability Data
OneUptime is a solution for monitoring and managing online services. In version 10.0.11 and prior, the WebAuthn authentication implementation does not store the challenge on the server side. Instead, the challenge is returned to the client and accepted back from…
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the client request body during verification. This violates the WebAuthn specification (W3C Web Authentication Level 2, §13.4.3) and allows an attacker who has obtained a valid WebAuthn assertion (e.g., via XSS, MitM, or log exposure) to replay it indefinitely, completely bypassing the second-factor authentication. No known patches are available.
- CWE(s)
Related Threats
MITRE ATT&CK Enterprise Techniques
CVEs Like This One
Affected Assets
Mitigating Controls
Control response
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- 8 hardening rules · 5 OS baselines
V6.4.4V6.5.4V6.5.5V6.5.7
Mitigating Controls (NIST 800-53 r5) AI
Mandates unique identification and authentication of organizational users before access, directly stopping improper authentication.
Requires unique identification and authentication of devices before establishing connections, preventing unauthenticated device claims.
Mandates unique identification and authentication of non-organizational users, directly addressing the weakness for external actors.
Session authenticity mechanisms directly stop replay of captured authentication traffic by enforcing freshness or cryptographic binding.
Manages authenticators with verification and secure distribution, reducing opportunities for improper authentication.
Transmission integrity (with anti-replay) stops captured messages from being accepted as valid later.
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.
PR.AA-03 directly enforces authentication mechanisms that eliminate most improper-authentication defects, yet CWE-287 spans additional vectors (missing checks, flawed protocols, session handling) that one control does not fully close.
PR.AA-04 directly enables verification of identity assertions (mostly preventing CWE-287 in that scope) yet leaves many other authentication failure modes unaddressed (only partial prevention overall).
Encryption and integrity protections for data-in-transit directly block capture-replay of credentials or tokens.
Network monitoring may detect anomalous replays after the fact but does not prevent the design flaw.
PR.AA-01 supplies and governs credentials/tokens that authentication relies on, removing some weak-credential cases, yet leaves verification logic, missing checks, and protocol flaws untouched.
PR.AA-02 ensures valid enrollment and unique credential binding, which reduces some improper-auth risks at issuance time but leaves runtime claim verification untouched, so each direction only partially addresses the other.
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.
Requiring authentication methods whose strength matches the sensitivity of the data and mandating multi-factor authentication directly blocks attempts to access resources without proving identity.
Verifying user identity before issuing replacement credentials and forcing changes after compromise reduces the likelihood that authentication bypass can be achieved through stolen or weak credentials.
Cryptographic protections (e.g., nonces, timestamps, message authentication codes) make captured authentication messages unusable for replay.
Mandating segregated approval and oversight for non-human identities reduces the chance that weak or orphaned credentials can be exploited for unauthorized authentication.
Network security controls such as encryption and integrity protection reduce the feasibility of capturing and replaying authentication traffic.
Requiring authentication mechanisms and technical parameters for secure connections ensures that network services verify user identity before granting access, preventing exploitation of missing or weak authentication.
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 (1 rule)
- V-248827 OL 8 must not have the rsh-server package installed. prevents CWE-287
RHEL 7 (3 rules)
- V-204425 The Red Hat Enterprise Linux operating system must be configured so that the SSH daemon does not allow authentication using an empty password. prevents CWE-287
- V-204442 The Red Hat Enterprise Linux operating system must not have the rsh-server package installed. prevents CWE-287
- V-204424 The Red Hat Enterprise Linux operating system must not allow accounts configured with blank or null passwords. prevents CWE-287
RHEL 8 (1 rule)
- V-230492 RHEL 8 must not have the rsh-server package installed. prevents CWE-287
Ubuntu 22.04 (1 rule)
- V-260470 Ubuntu 22.04 LTS, when booted, must require authentication upon booting into single-user and maintenance modes. prevents CWE-287
Ubuntu 24.04 (2 rules)
- V-270675 Ubuntu 24.04 LTS when booted must require authentication upon booting into single-user and maintenance modes. prevents CWE-287
- V-270714 Ubuntu 24.04 LTS must not allow accounts configured in Pluggable Authentication Modules (PAM) with blank or null passwords. prevents CWE-287