Security researcher Muneaki Nishimura (nishimunea) of Recruit Technologies Co.,Ltd. reported that Content Security Policy (CSP) violation reports contained full path information for cross-origin iframe navigations in violation of the CSP specification. This could result in information disclosure.
In general this flaw cannot be exploited through email in the Thunderbird product because scripting is disabled, but is potentially a risk in browser or browser-like contexts.