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TI-2025-40969 Aliases CVE-2025-66558

Nextcloud Twofactor WebAuthn app was updated based on public key

Priority LOW 20CWE-639Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Security bypass
Confidentiality · integrity · availability
None · Low · None
Fix status
Fixed

Attack profile from CVSS 3.1 · NVD. Fix status from CNA. Impact type from CWE-639.

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 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.

Why it matters now

Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00298 22nd percentileScored 2026-11-07
Fix Fixed security-advisories (nextcloud): 1.4.2, 2.4.1

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
None
Automatable
No
Technical impact
Partial

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
nextcloudsecurity-advisoriesbefore 1.4.2; 2.0.0-beta.1 to before 2.4.11.4.2, 2.4.1Patch availableCNA
  • security-advisories Vendornextcloud Affected before 1.4.2; 2.0.0-beta.1 to before 2.4.1 Fixed in 1.4.2, 2.4.1 Patch available CNA

CPE configurations NVD · 1

CPEVersionsRoleVendor
cpe:2.3:a:nextcloud:two-factor_webauthn:*:*:*:*:*:*:*:*1.0.0 to before 1.4.2; 2.0.0 to before 2.4.1Vulnerablenextcloud
  • cpe:2.3:a:nextcloud:two-factor_webauthn:*:*:*:*:*:*:*:* Versions 1.0.0 to before 1.4.2; 2.0.0 to before 2.4.1 Vulnerable ·nextcloud

Remediation

  • Fix · CNA security-advisories (nextcloud) Fixed in 1.4.2, 2.4.1

Timeline

  1. 2026-10-02 Threatist record created from CVE-2025-66558

References

Patch 3

Advisory 1

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences