CVE-2025-66558

MEDIUM EPSS 13.3%
Published Dec 5, 20256mo ago · Modified Jun 17, 20261w ago
4.3 CVSS 3.1
Medium
Find Similar
Published Dec 5, 2025 6mo ago
Last Modified Jun 17, 2026 1w ago

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.

CVSS Details

Base Score
4.3
Exploitability
2.8
Impact
1.4
Vector string
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N
Attack Vector Network
Attack Complexity Low
Privileges Required None
User Interaction Required
Scope Unchanged
Confidentiality None
Integrity Low
Availability None

Threat Intelligence

EPSS Exploit Probability
13.3% percentile
Exploit & Patch Status
No Known Exploit
Patch Available

Weaknesses 1

CWE-639

Affected Products 2

VendorProductVersionRange
nextcloudtwo-factor_webauthn*≥1.0.0  –  <1.4.2
nextcloudtwo-factor_webauthn*≥2.0.0  –  <2.4.1

References 4

  • github.com https://github.com/nextcloud/security-advisories/security/advisories/GHSA-fr8x-mvjg-wf9q
    PatchVendor Advisory
  • github.com https://github.com/nextcloud/twofactor_webauthn/commit/5d2302166d31ee2e01b2e21556bd5372156da13d
    Patch
  • github.com https://github.com/nextcloud/twofactor_webauthn/pull/881
    Issue TrackingPatch
  • hackerone.com https://hackerone.com/reports/3360354
    Permissions RequiredVendor Advisory

Remediation

  • github.com https://github.com/nextcloud/security-advisories/security/advisories/GHSA-fr8x-mvjg-wf9q
    PatchVendor Advisory
  • github.com https://github.com/nextcloud/twofactor_webauthn/commit/5d2302166d31ee2e01b2e21556bd5372156da13d
    Patch
  • github.com https://github.com/nextcloud/twofactor_webauthn/pull/881
    Issue TrackingPatch