CVE-2025-66558

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 v3.1 Score

3.1

LOW

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

Weakness Type (CWE)

CWE-639 CWE-639

Affected Products

Vendor	Product	Versions
nextcloud	two-factor_webauthn	1.0.0 — 1.4.2
nextcloud	two-factor_webauthn	2.0.0 — 2.4.1

References

Advisories & Patches

https://github.com/nextcloud/security-advisories/security/advisories/GHSA-fr8x-mvjg-wf9q https://github.com/nextcloud/twofactor_webauthn/commit/5d2302166d31ee2e01b2e21556bd5372156da13d https://github.com/nextcloud/twofactor_webauthn/pull/881 https://hackerone.com/reports/3360354

Frequently Asked Questions

What is CVE-2025-66558? +

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. It has a CVSS v3.1 base score of 3.1 (LOW).

How severe is CVE-2025-66558? +

CVE-2025-66558 has a CVSS v3.1 score of 3.1 out of 10, rated LOW. This is a low-severity vulnerability with limited impact.

What products are affected by CVE-2025-66558? +

CVE-2025-66558 affects products from nextcloud, specifically: two-factor_webauthn. Check the affected products table above for specific version ranges.

How do I check if I'm vulnerable to CVE-2025-66558? +

You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

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