Christophwurst

**Name of the Vulnerable Software and Affected Versions** Nextcloud Server versions 25.0.0 through 25.0.7 Nextcloud Server versions 26.0.0 through 26.0.2 Nextcloud Enterprise Server versions 21.0.0 through 21.0.9.12 Nextcloud Enterprise Server versions 22.0.0 through 22.2.10.12 Nextcloud Enterprise Server versions 23.0.0 through 23.0.12.7 Nextcloud Enterprise Server versions 24.0.0 through 24.0.12.2 Nextcloud Enterprise Server versions 25.0.0 through 25.0.7 Nextcloud Enterprise Server versions 26.0.0 through 26.0.2 **Description** The issue is related to inadequate access control in the index.php component of Nextcloud Server and Nextcloud Enterprise Server, which are part of a self-hosted productivity platform providing file storage for Nextcloud. When two servers are registered as trusted servers for each other and have successfully exchanged share secrets, a malicious server could modify or delete VCards in the system address book on the origin server. This would impact the available and shown information in certain places, such as the user search and avatar menu. If a manipulated user modifies their own data in the personal settings, the entry is fixed again. **Recommendations** For Nextcloud Server versions 25.0.0 through 25.0.7, update to version 25.0.7 or later. For Nextcloud Server versions 26.0.0 through 26.0.2, update to version 26.0.2 or later. For Nextcloud Enterprise Server versions 21.0.0 through 21.0.9.12, update to version 21.0.9.12 or later. For Nextcloud Enterprise Server versions 22.0.0 through 22.2.10.12, update to version 22.2.10.12 or later. For Nextcloud Enterprise Server versions 23.0.0 through 23.0.12.7, update to version 23.0.12.7 or later. For Nextcloud Enterprise Server versions 24.0.0 through 24.0.12.2, update to version 24.0.12.2 or later. For Nextcloud Enterprise Server versions 25.0.0 through 25.0.7, update to version 25.0.7 or later. For Nextcloud Enterprise Server versions 26.0.0 through 26.0.2, update to version 26.0.2 or later. As a temporary workaround, remove all trusted servers in the "Administration" > "Sharing" settings `/index.php/settings/admin/sharing`. Afterwards, trigger a recreation of the local system address book with the following `occ dav:sync-system-addressbook`.

**Name of the Vulnerable Software and Affected Versions** Nextcloud Contacts app versions prior to 4.2.4 Nextcloud Contacts app versions prior to 5.0.3 **Description** The issue concerns the handling of unsanitized SVG files in the Contacts app for Nextcloud. These files are converted into JavaScript blobs, which the Avatar component cannot render. Although the missing sanitization is present, it does not seem to be exploitable due to this specific implementation. **Recommendations** For versions prior to 4.2.4, upgrade to version 4.2.4. For versions prior to 5.0.3, upgrade to version 5.0.3.

**Name of the Vulnerable Software and Affected Versions** Nextcloud Mail versions prior to 2.2.2 **Description** The issue concerns the storage of user passwords in cleartext in the database during the OAuth2 setup procedure. Any attacker or malicious user with access to the database would have access to these user passwords until the OAuth setup has been completed. **Recommendations** For versions prior to 2.2.2, upgrade the Nextcloud Mail app to 2.2.2 to resolve the issue. As a temporary workaround, consider restricting access to the database to minimize the risk of exploitation.