Nextcloud global site selector authentication bypass

Successful exploitation of CVE-2024-22212 grants an attacker the ability to impersonate any user within the Nextcloud environment managed by the Global Site Selector. This can lead to unauthorized data access, modification, or deletion. The attacker could potentially gain administrative privileges, allowing them to compromise the entire Nextcloud instance. The scope of impact depends on the permissions granted to the impersonated user; a user with limited access will grant limited access to the attacker, while an administrator account provides full control. This vulnerability is particularly concerning given Nextcloud's widespread use for file sharing and collaboration, often containing sensitive business or personal data.

Organizations utilizing Nextcloud with the Global Site Selector enabled are at risk. This includes businesses relying on Nextcloud for file sharing, collaboration, and document management. Specifically, environments with multiple Nextcloud instances managed by the Global Site Selector are particularly vulnerable, as the attacker can potentially pivot between instances after gaining access to one.

• php: Examine Nextcloud logs for unusual authentication patterns or failed login attempts followed by successful access.

 grep "authentication failed" /path/to/nextcloud/data/nextcloud.log

• generic web: Monitor access logs for requests targeting the Global Site Selector endpoint with unusual parameters.

 grep "/global_site_selector/" /var/log/apache2/access.log

1. 2024-01-18Disclosure

   disclosure

1. Reserviert2024-01-08
2. Veröffentlicht2024-01-18
3. Geändert2024-09-11
4. EPSS aktualisiert2026-04-02

The primary mitigation for CVE-2024-22212 is to immediately upgrade the Nextcloud Global Site Selector to version 1.4.1, 2.1.2, 2.3.4, or 2.4.5. Due to the nature of the authentication bypass, there are no known workarounds beyond upgrading. If an immediate upgrade is not feasible due to compatibility issues or testing requirements, consider temporarily restricting access to the Global Site Selector functionality until the upgrade can be performed. Monitor Nextcloud logs for any suspicious authentication attempts or unusual user activity. After upgrading, verify the fix by attempting to authenticate with a different user account and confirming that the authentication bypass is no longer possible.