Applio Server-Side Request Forgery and File Write Vulnerability Allowing Remote Code Execution

A server-side request forgery (SSRF) vulnerability has been identified in Applio, a voice conversion tool, in versions through 3.2.7. The vulnerability resides in the 'model_download.py' file, specifically at line 143. This blind SSRF allows the Applio server to send requests on behalf of the user, potentially probing for other vulnerabilities on the server or internal network. Additionally, the vulnerability includes an arbitrary file write feature, enabling files to be written on the server. This file write capability could be combined with other vulnerabilities, such as unsafe deserialization, to achieve remote code execution on the Applio server.

Impact

The blind SSRF can be exploited to read files from internal network hosts accessible to the Applio server, effectively turning it into a full SSRF. The arbitrary file write can be used to place files on the Applio server, which, when paired with certain vulnerabilities like unsafe deserialization, could lead to remote code execution.

Reproduction

The vulnerability can be reproduced by uploading a file through the application's interface that accepts model files. The 'model_download.py' script will then download the file from the provided URL, writing it to the server. This process can be monitored to confirm the file write action.