Nextcloud Server up to 32.0.8/33.0.2 DAV Endpoint improper authentication

Summaryinfo

A vulnerability was found in Nextcloud Server up to 32.0.8/33.0.2. It has been declared as critical. This vulnerability affects unknown code of the component DAV Endpoint. Executing a manipulation can lead to improper authentication. The identification of this vulnerability is CVE-2026-45691. The attack may be launched remotely. There is no exploit available. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability has been found in Nextcloud Server up to 32.0.8/33.0.2 and classified as critical. This vulnerability affects some unknown processing of the component DAV Endpoint. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect integrity, and availability. CVE summarizes:

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, a pre-2FA session cookie (created after successful password authentication but before TOTP completion) could be reused as a Bearer token to authenticate against DAV endpoints, granting read/write access and bypassing mandatory two-factor authentication. 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

The advisory is shared for download at github.com. This vulnerability was named CVE-2026-45691 since 05/13/2026. The exploitation appears to be difficult. The attack can be initiated remotely. No form of authentication is required for a successful exploitation. There are neither technical details nor an exploit publicly available.

Upgrading to version 32.0.9 or 33.0.3 eliminates this vulnerability. Applying a patch is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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Productinfo

Type

• Cloud Software

Vendor

• Nextcloud

Name

• Server

Version

• 32.0.0
• 32.0.1
• 32.0.2
• 32.0.3
• 32.0.4
• 32.0.5
• 32.0.6
• 32.0.7
• 32.0.8
• 33.0.0
• 33.0.1
• 33.0.2

License

• open-source

Website

• Product: https://github.com/nextcloud/server/

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