What is CVE-2021-38299?

CVE-2021-38299 is a critical-severity vulnerability in Spomky-Labs Webauthn Framwork, classified under Improper Authentication. CVSS score: 9.8/10. Published 2021-09-27.

How severe is CVE-2021-38299?

Critical severity. CVSS v3 base score is 9.8 out of 10.

Auth bypass in Spomky-Labs Webauthn Framwork

CVE-2021-38299

Webauthn Framework 3.3.x before 3.3.4 has Incorrect Access Control. An attacker that controls a user's system is able to login to a vulnerable service using an attached FIDO2 authenticator without passing a check of the user presence.

Vulnerability class: Broken Authentication

Published 2021-09-27 · last modified 2026-06-17.

CVSS v3 metric

CVSS v3 base score 9.8 (Critical). Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

EPSS exploit prediction

EPSS: 0.018 (77.6th percentile), scored 2026-09-30.

Low probability of exploitation in the next 30 days, but still tracked. 78th percentile — 77.6% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS over last 30 days · oldest: 0.018 · newest: 0.018 · change: 0.000

Affected products

Spomky-Labs Webauthn Framwork

Weakness classification (CWE)

CWE-287 — Improper Authentication

References

github.com/web-auth/webauthn-framework/releases (Third Party Advisory, Release Notes)
www.fzi.de/en/news/news/detail-en/artikel/fsa-2021-1-fehlende-ueberpruefung-von… (Third Party Advisory)

Frequently asked questions

What is CVE-2021-38299?: CVE-2021-38299 is a critical-severity vulnerability in Spomky-Labs Webauthn Framwork, classified under Improper Authentication. CVSS score: 9.8/10. Published 2021-09-27.
How severe is CVE-2021-38299?: Critical severity. CVSS v3 base score is 9.8 out of 10.