Mozilla Firefox Same-Origin Policy Bypass via JAR URI Handling

Successful exploitation allows a network-based attacker to bypass fundamental browser security boundaries without requiring any user interaction or elevated privileges. This can lead to unauthorized access to sensitive cross-origin data including authentication tokens, session cookies, and personal information from other origins. The combination of a network attack vector, low attack complexity, and no authentication requirement means this vulnerability could be exploited at scale against any user running a vulnerable version of Firefox or Thunderbird, potentially resulting in complete compromise of user sessions and sensitive data exfiltration.