CVE-2026-45690 MEDIUM

CVE-2026-45690: Nextcloud: Two-Factor Authentication Bypass via Pending Session Token Replay

Vendor Nextcloud
Product security-advisories
Weakness CWE-287 · Improper authentication
Published June 1, 2026
Last update June 2, 2026

CVSS base score

5.9/10
Attack vector Network
Attack complexity High
Privileges required Low
User interaction None
Confidentiality Low
Integrity High

CVSS vector

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

What the vulnerability does

01Description

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

Key dates

02Disclosure timeline

June 1, 2026 CVE published
June 2, 2026 Record updated