Mozilla · Firefox · CVE-2017-5384
**Name of the Vulnerable Software and Affected Versions**
Firefox versions prior to 51
**Description**
The issue concerns Proxy Auto-Config (PAC) files, which can specify a JavaScript function that is called for all URL requests, potentially exposing more information than would be sent to the proxy itself in the case of HTTPS. Normally, the Proxy Auto-Config file is presumed to be non-malicious, but if a user has enabled Web Proxy Auto Detect (WPAD), this file can be served remotely, introducing a potential risk.
**Recommendations**
For Firefox versions prior to 51, update to version 51 or later to resolve the issue. As a temporary workaround, consider disabling Web Proxy Auto Detect (WPAD) to minimize the risk of exploitation. Restrict access to remote Proxy Auto-Config files to prevent potential malicious activity.