CVE-2025-66558
low-risk
Published 2025-12-05
Nextcloud Twofactor WebAuthn is the WebAuthn Two-Factor Provider for Nextcloud. Prior to 1.4.2 and 2.4.1, a missing ownership check allowed an attack to take-away a 2FA webauthn device when correctly guessing a 80-128 character long random string of letters, numbers and symbols. The victim would then be prompted to register a new device on the next login. The attacker can not authenticate as the victim. This vulnerability is fixed in 1.4.2 and 2.4.1.
Do I need to act?
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0.03% chance of exploitation
EPSS score — low exploit probability
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Not on CISA KEV list
No confirmed active exploitation reported to CISA
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Patch status unknown
Check vendor advisories for fix availability and mitigation guidance
3
CVSS 3.1/10
Low
NETWORK
/ HIGH complexity
Affected Products (1)
Two-Factor Webauthn
Affected Vendors
References (4)
Issue Tracking
https://github.com/nextcloud/twofactor_webauthn/pull/881
Permissions Required
https://hackerone.com/reports/3360354
16
/ 100
low-risk
Severity
11/34 · Low
Exploitability
0/34 · Minimal
Exposure
5/34 · Minimal