Zero-Day Advisory

Fortinet Discovers Nextcloud Insufficient Input Validation Vulnerability


Fortinet's FortiGuard Labs has discovered an insufficient input validation vulnerability in Nextcloud.

Nextcloud is a suite of client-server software for creating file hosting services.

An input insufficient validation vulnerability has been discovered in Nextcloud before 12.0.3 and 11.0.5. Improper validation of user input allows an attacker to not have their actions logged to the audit log.


FortiGuard Labs released the following FortiGate IPS signature which covers this specific vulnerability:

Released May 30, 2017

Users should apply the solution provided by Nextcloud.


Fortinet reported the vulnerability to Nextcloud on May 26, 2017.

Nextcloud confirmed the vulnerability on May 27, 2017.

Nextcloud patched the vulnerability  on September 20, 2017.


This vulnerability was discovered by Zhouyuan Yang of Fortinet's FortiGuard Labs.

IPS Subscription

Fortinet customers who subscribe to Fortinet's intrusion prevention (IPS) service should be protected against this vulnerability with the appropriate configuration parameters in place. Fortinet's IPS service is one component of FortiGuard Subscription Services, which also offer comprehensive solutions such as antivirus, Web content filtering and antispam capabilities. These services enable protection against threats on both application and network layers. FortiGuard Services are continuously updated by FortiGuard Labs, which enables Fortinet to deliver a combination of multi-layered security intelligence and true zero-day protection from new and emerging threats. These updates are delivered to all FortiGate, FortiMail and FortiClient products. Fortinet strictly follows responsible disclosure guidelines to ensure optimum protection during a threat's lifecycle.