CVE-2026-45690: CWE-287: Improper Authentication in nextcloud security-advisories
Nextcloud Server versions 32.0.0 to before 32.0.9 and 33.0.0 to before 33.0.3 contain an authentication bypass vulnerability that allows attackers who know a user's password to bypass two-factor authentication (2FA). The issue arises because a temporary session token is created before the second factor challenge is enforced, which can be extracted and replayed via HTTP Basic Authentication to access authenticated endpoints without completing 2FA. Upgrading to versions 32.0.9 or 33.0.3 (or later) resolves this vulnerability.
AI Analysis
Technical Summary
Nextcloud Server versions >=32.0.0 <32.0.9 and >=33.0.0 <33.0.3 have an authentication bypass vulnerability (CWE-287) where an attacker with valid user credentials can circumvent 2FA protections. This occurs because the system generates a temporary session token prior to enforcing the second factor challenge. This token can be extracted and replayed using HTTP Basic Authentication to gain unauthorized access to endpoints that require authentication. The vulnerability is fixed in Nextcloud Server versions 32.0.9 and 33.0.3, with additional fixes for Enterprise Server versions 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, and 29.0.16.16.
Potential Impact
An attacker who knows a user's password can bypass the two-factor authentication mechanism, allowing unauthorized access to user accounts and authenticated endpoints. This compromises the integrity of the authentication process and increases the risk of account takeover despite 2FA being enabled. The confidentiality of user data may be partially impacted (low confidentiality impact), and the integrity of user sessions is highly impacted (high integrity impact). Availability is not affected.
Mitigation Recommendations
A fix is available. It is recommended to upgrade Nextcloud Server to version 32.0.9 or 33.0.3 or later. For Nextcloud Enterprise Server, upgrade to versions 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, or 29.0.16.16. No other mitigation steps are indicated by the vendor advisory.
CVE-2026-45690: CWE-287: Improper Authentication in nextcloud security-advisories
Description
Nextcloud Server versions 32.0.0 to before 32.0.9 and 33.0.0 to before 33.0.3 contain an authentication bypass vulnerability that allows attackers who know a user's password to bypass two-factor authentication (2FA). The issue arises because a temporary session token is created before the second factor challenge is enforced, which can be extracted and replayed via HTTP Basic Authentication to access authenticated endpoints without completing 2FA. Upgrading to versions 32.0.9 or 33.0.3 (or later) resolves this vulnerability.
CVSS v3.1
Score 5.9medium
Affected software
pkg:github/nextcloud/serverRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
Nextcloud Server versions >=32.0.0 <32.0.9 and >=33.0.0 <33.0.3 have an authentication bypass vulnerability (CWE-287) where an attacker with valid user credentials can circumvent 2FA protections. This occurs because the system generates a temporary session token prior to enforcing the second factor challenge. This token can be extracted and replayed using HTTP Basic Authentication to gain unauthorized access to endpoints that require authentication. The vulnerability is fixed in Nextcloud Server versions 32.0.9 and 33.0.3, with additional fixes for Enterprise Server versions 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, and 29.0.16.16.
Potential Impact
An attacker who knows a user's password can bypass the two-factor authentication mechanism, allowing unauthorized access to user accounts and authenticated endpoints. This compromises the integrity of the authentication process and increases the risk of account takeover despite 2FA being enabled. The confidentiality of user data may be partially impacted (low confidentiality impact), and the integrity of user sessions is highly impacted (high integrity impact). Availability is not affected.
Mitigation Recommendations
A fix is available. It is recommended to upgrade Nextcloud Server to version 32.0.9 or 33.0.3 or later. For Nextcloud Enterprise Server, upgrade to versions 33.0.3, 32.0.9, 31.0.14.5, 30.0.17.9, or 29.0.16.16. No other mitigation steps are indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-05-13T04:38:01.164Z
- Cvss Version
- 3.1
- State
- PUBLISHED
- Remediation Level
- null
Threat ID: 6a1de30be29bf47b503a5703
Added to database: 06/01/2026, 19:52:43 UTC
Last enriched: 07/13/2026, 09:54:18 UTC
Last updated: 07/31/2026, 19:22:59 UTC
Views: 320
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