CVE-2025-66558

mediumpriority · track · 17EPSS 0.003 · 20 %ileDEEUUS

grimoire priorityP3 · Track

Exploitable?

—

no known exploitation

Likely / severe?

0.28% (20th) EPSS

CVSS 4.3 · medium

Is it mine?

8 products

Check your exposure

Who says so?

4 sources

cnnvd · enisa_euvd · cert_bund · nvd

EPSS · scored 2026-10-28

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

Technical severity, 0–10. One row per scoring source.

4.3

010

base score 0–10 · higher = more severe · hover a vector to decode⚠ sources disagree · low–medium · 3.1–4.3

v3.14.3mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:Nprimary · NVD / NIST USexploitability 2.8 · impact 1.4

v3.13.1lowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:Nsecondary · ENISA EU

v3.13.1lowCVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:L/A:Nsecondary · security-advisories@github.comexploitability 1.6 · impact 1.4

v3.14mediumCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:L/A:N/E:Usecondary · CVSS-BT (t0sche)

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Trackcoordinatorcisa_ssvcUS

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-639US

affected products (8)

Products and version ranges known to be affected.

Nextcloud Nextcloud Twofactor WebAuthn <1.4.2all versionscert_bundDE
Nextcloud Nextcloud Twofactor WebAuthn <2.4.1all versionscert_bundDE
nextcloud nextcloud≤ Twofactor WebAuthn <1.4.2cert_bundDE
nextcloud nextcloud≤ Twofactor WebAuthn <2.4.1cert_bundDE
nextcloud security-advisories≤ < 1.4.2enisa_euvdEU
nextcloud security-advisories2.0.0-beta.1, → 2.4.1enisa_euvdEU
nextcloud two-factor webauthn1.0.0 → 1.4.2nvdUScpe:2.3:a:nextcloud:two-factor_webauthn:*:*:*:*:*:*:*:*
nextcloud two-factor webauthn2.0.0 → 2.4.1nvdUScpe:2.3:a:nextcloud:two-factor_webauthn:*:*:*:*:*:*:*:*

advisories (1)

Vendor and ecosystem advisories describing this.

WID-SEC-W-2025-2757Nextcloud (Contacts, Talk, Deck und Twofactor WebAuthn): Mehrere SchwachstellenDeutsch2025-12-07csaf · cert_bundDE
Ein Angreifer kann mehrere Schwachstellen in Nextcloud ausnutzen, um einen Cross-Site Scripting Angriff durchzuführen, um Dateien zu manipulieren, und um Sicherheitsvorkehrungen zu umgehen.

also known as (2)

Other names and identifiers for this entity.

sources

Which sources assert this record, and when.

cnnvd enisa_euvd cert_bund nvd NVD CVE.org MITRE

published 2025-12-05modified 2026-06-17

references (13)

External citations — patches, advisories, analysis.

scry

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