CVE-2026-28787CWE-287CWE-294

OneUptime has WebAuthn 2FA bypass: server accepts client-supplied challenge instead of server-stored value, allowing credential replay

High · published March 6, 2026

CVSS v3.1
8.2
EPSS
0%
Percentile
32.6
In the wild
Unconfirmed
What it is

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 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.

The record
Technical detail
CVSS v3.1
8.2 · HIGH
Vector
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
CVSS v4.0
Not supplied
EPSS
0.00396 · 32.6th percentile
Weaknesses
CWE-287 · Improper Authentication; CWE-294 · Authentication Bypass by Capture-replay
Published
2026-03-06T04:55Z
EPSS history
Timeline
  • 06 MAR 04:55Z
    OneUptime has WebAuthn 2FA bypass: server accepts client-supplied challenge instead of server-stored value, allowing credential replay
    cvelistv5