---
id: CVE-2025-66558
title: Nextcloud Twofactor WebAuthn is the WebAuthn Two-Factor Provider for Nextcloud
summary: >-
  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 rand…
severity: low
cvss: 3.1
cvssVector: 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:N'
cwe:
  - CWE-639
vendor: nextcloud
product: two-factor_webauthn
affected:
  - 'two-factor_webauthn >= 1.0.0, < 1.4.2'
  - 'two-factor_webauthn >= 2.0.0, < 2.4.1'
patched:
  - two-factor_webauthn 2.4.1
published: '2025-12-05'
updated: '2026-10-15'
sourceUpdated: '2026-10-15T21:10:00.327'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2025-66558'
references:
  - url: >-
      https://github.com/nextcloud/security-advisories/security/advisories/GHSA-fr8x-mvjg-wf9q
    label: security-advisories@github.com
  - url: >-
      https://github.com/nextcloud/twofactor_webauthn/commit/5d2302166d31ee2e01b2e21556bd5372156da13d
    label: security-advisories@github.com
  - url: 'https://github.com/nextcloud/twofactor_webauthn/pull/881'
    label: security-advisories@github.com
  - url: 'https://hackerone.com/reports/3360354'
    label: security-advisories@github.com
tags:
  - nvd
epss: 0.00278
epssPercentile: 0.20166
ingestedAt: '2026-10-27T18:12:09.281Z'
---

## Overview

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.

## Affected

- `two-factor_webauthn >= 1.0.0, < 1.4.2`
- `two-factor_webauthn >= 2.0.0, < 2.4.1`

## Remediation

Upgrade past the affected range:

- `two-factor_webauthn 2.4.1`