CVE-2025-66558 | BDVDB-2026-304103 Detail

nextcloudsecurity-advisories

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.

Impact#

Per CVSS v3.1: confidentiality impact none, integrity impact low, availability impact none. Attack vector: network.

Weaknesses#

CWE-639 Authorization Bypass Through User-Controlled Key

References#

Exploit#

No public exploit known

History#

Version 12025-12-05Record published in the CVE List.

Published

Published: 2025-12-05
Last modified: 2025-12-05

Vendor information

Vendor: nextcloud
Product: security-advisories

All nextcloud vulnerabilities

Score

3.1 Low

EPSS

less than 1%, Very Low

Estimated chance of exploitation in the next 30 days. EPSS percentile: 22.7.

KEV

Not listed in the CISA Known Exploited Vulnerabilities catalog.

Impact

Insecure Direct Object Reference

Action

No specific action is recorded in the source data. Check the references for vendor guidance.

Affected Systems

Vulnerable
< 1.4.2
Fixed
Not stated
Vulnerable
>= 2.0.0-beta.1, < 2.4.1
Fixed
Not stated

Scoring System

CVSS v4.0

Not available

CVSS v3.1

3.1 Low

CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N

Metric breakdown
Attack Vector	Network
Attack Complexity	High
Privileges Required	Low
User Interaction	None
Scope	Unchanged
Confidentiality	None
Integrity	Low
Availability	None

CVSS v3.0

Not available

CVSS v2

Not available

Source: CVE List v5 (record); CISA KEV (kev, action); FIRST EPSS (epss).