Nextcloud Server 2FA Auth Bypass v32.0.0-32.0.8, 33.0.0-33.0.2
CVE-2026-45690 Published on June 1, 2026
Nextcloud: Two-Factor Authentication Bypass via Pending Session Token Replay
Nextcloud is an open source content collaboration platform. In Nextcloud Server from versions 32.0.0 to before 32.0.9, and 33.0.0 to before 33.0.3, an authentication bypass vulnerability allowed attackers with knowledge of a user's password to circumvent two-factor authentication (2FA) protections. When a user initiated login with valid credentials on a 2FA-enabled account, the system created a temporary session token before enforcing the second factor challenge. This token could be extracted and replayed via HTTP Basic Authentication to gain unauthorized access to authenticated endpoints. It is recommended that the Nextcloud Server is upgraded to 33.0.3 or 32.0.9. It is recommended that the Nextcloud Enterprise Server is upgraded to 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9 or 29.0.16.16
Vulnerability Analysis
CVE-2026-45690 is exploitable with network access, and requires small amount of user privileges. This vulnerability is consided to have a high level of attack complexity. The potential impact of an exploit of this vulnerability is considered to have a small impact on confidentiality, a high impact on integrity, and no impact on availability.
Weakness Type
What is an authentification Vulnerability?
When an actor claims to have a given identity, the software does not prove or insufficiently proves that the claim is correct.
CVE-2026-45690 has been classified to as an authentification vulnerability or weakness.
Affected Versions
nextcloud security-advisories:- Version >= 32.0.0, < 32.0.9 is affected.
- Version >= 33.0.0, < 33.0.3 is affected.