CVE-2025-665583.1LowCWE-639

CVE-2025-66558: Nextcloud Twofactor WebAuthn app was updated based on public key

nextcloud · security-advisories

Affected: nextcloud security-advisories · Exploitation: unlikely (under 1%)

Not in CyberSIXT coverage yet: no article names this CVE. This page shows the public record.

0.3%probability of exploitation in the next 30 days

22nd percentile

050100

Higher than 22% of scored CVEs

3.1LowCVSS 3.1

LowMediumHighCrit.

DescriptionCVE.org

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 products1

From the CVE record. A product or version that is not listed is unknown, not unaffected.

nextcloud · security-advisories< 1.4.2; >= 2.0.0-beta.1, < 2.4.1

On the Atlas

Every published CVE is on the CyberSIXT Atlas, grouped by weakness, vendor and month.

Open the Atlas

Exploitation: Unlikely (under 1%). EPSS under 1%, or no score yet.
CISA KEV: Not listed
Public check: No public nuclei template
Weakness: Insecure Direct Object Reference
Vendor: nextcloud
Published: December 2025
Band: Unlikely (under 1%), December 2025
Bounty reports: 1 disclosed on HackerOne

Disclosed bug bounty reports about CVE-2025-66558

The reports on HackerOne that name this CVE, with HackerOne's own outcome. Titles and metadata only.

WebAuthn app was updated based on public keyNextcloud · 2026 · low severityValid

CoverageNo articles yet

No CyberSIXT article names CVE-2025-66558 yet, so there is no coverage timeline, action brief or change log for it. Everything on this page comes from the public CVE record, CISA KEV, EPSS and the nuclei template index. Search the archive or see the CVEs in the news.