A use-after-free vulnerability can occur during font face manipulation when a font face is freed while still in use, resulting in a potentially exploitable crash. This vulnerability affects Thunderbird < 52.6, Firefox ESR < 52.6, and Firefox < 58.
Memory safety bugs were reported in Firefox 56 and Firefox ESR 52.4. Some of these bugs showed evidence of memory corruption and we presume that with enough effort that some of these could be exploited to run arbitrary code. This vulnerability affects Firefox < 57, Firefox ESR < 52.5, and Thunderbird < 52.5.
A use-after-free vulnerability can occur when flushing and resizing layout because the "PressShell" object has been freed while still in use. This results in a potentially exploitable crash during these operations. This vulnerability affects Firefox < 57, Firefox ESR < 52.5, and Thunderbird < 52.5.
The Resource Timing API incorrectly revealed navigations in cross-origin iframes. This is a same-origin policy violation and could allow for data theft of URLs loaded by users. This vulnerability affects Firefox < 57, Firefox ESR < 52.5, and Thunderbird < 52.5.
When Private Browsing mode is used, it is possible for a web worker to write persistent data to IndexedDB and fingerprint a user uniquely. IndexedDB should not be available in Private Browsing mode and this stored data will persist across multiple private browsing mode sessions because it is not cleared when exiting. This vulnerability affects Firefox ESR < 52.5.2 and Firefox < 57.0.1.