Zero-Day Advisory

Fortinet Discovers Mruby Heap Use-After-Free Vulnerability


Fortinet's FortiGuard Labs has discovered a heap Use-After-Free vulnerability in Mruby.

Mruby is an interpreter for the Ruby programming language with the intention of being lightweight and easily embeddable. The project is headed by Yukihiro Matsumoto, with over 100 contributors currently working on the project.

A heap Use-After-Free vulnerability exists in Mruby. A successful exploit of this vulnerability will cause memory corruption and lead to DoS. Under some conditions, remote code execution is also possible.


Users should apply the solution provided by Mruby.

Additional Information

Fortinet reported the vulnerability to Mruby on February 22, 2017.

Mruby patched the vulnerability on April 9, 2017.


This vulnerability was discovered by Tien Phan 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.