CVE-2025-66558

Low

Description

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.

SeverityLow

CVSS3.1

Exploit probability—

Product

Nextcloud Two-factor Webauthn

PublishedDec 5, 2025

First seenDec 5, 2025

Weakness typeCWE-639Authorization bypass through user-controlled key

How to fix

Update

nextcloud two-factor_webauthn1.4.2, 2.4.1 or later

Affected products

Product	Affected versions	Fixed in
nextcloud two-factor_webauthn	1.0.0 ≤ v < 1.4.2, 2.0.0 ≤ v < 2.4.1	1.4.2, 2.4.1

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