Exposure of Sensitive Information to an Unauthorized Actor
The URL parsing implementation in Mozilla Firefox before 42.0 improperly recognizes escaped characters in hostnames within Location headers, which allows remote attackers to obtain sensitive information via vectors involving a redirect.
CWE-200 - Information Exposure
An information exposure vulnerability is categorized as an information flow (IF) weakness, which can potentially allow unauthorized access to otherwise classified information in the application, such as confidential personal information (demographics, financials, health records, etc.), business secrets, and the application's internal environment.