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CVE

CVE-2026-28787

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

CVE-2026-28787

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

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.

Package Versions Affected

Package Version
patch Availability
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CVSS Version

Severity
Base Score
CVSS Version
Score Vector
C
H
U
8.2
-
3.1
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
C
H
U
0
-
3.1
CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:H/I:H/A:N
C
H
U
-

Related Resources

No items found.

References

https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/28xxx/CVE-2026-28787.json, https://github.com/OneUptime/oneuptime/security/advisories/GHSA-gjjc-pcwp-c74m, https://nvd.nist.gov/vuln/detail/CVE-2026-28787

Severity

8.2

CVSS Score
0
10

Basic Information

Ecosystem
Base CVSS
8.2
EPSS Probability
0.00066%
EPSS Percentile
0.20568%
Introduced Version
0
Fix Available

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