A vulnerability in register allocation in JavaScript can lead to type confusion, allowing for an arbitrary read and write. This leads to remote code execution inside the sandboxed content process when triggered.

A potentially exploitable crash in TransportSecurityInfo used for SSL can be triggered by data stored in the local cache in the user profile directory. This issue is only exploitable in combination with another vulnerability allowing an attacker to write data into the local cache or from locally installed malware. This issue also triggers a non-exploitable startup crash for users switching between the Nightly and Release versions of Firefox if the same profile is used.

If a user saved passwords before Firefox 58 and then later set a master password, an unencrypted copy of these passwords is still accessible. This is because the older stored password file was not deleted when the data was copied to a new format starting in Firefox 58. The new master password is added only on the new file. This could allow the exposure of stored password data outside of user expectations.

Manually dragging and dropping an Outlook email message into the browser will trigger a page navigation when the message's mail columns are incorrectly interpreted as a URL. Note: this issue only affects Windows operating systems with Outlook installed. Other operating systems are not affected.

When the Mozilla Updater opens a MAR format file which contains a very long item filename, an out-of-bounds write can be triggered, leading to a potentially exploitable crash. This requires running the Mozilla Updater manually on the local system with the malicious MAR file in order to occur.

A use-after-free vulnerability can occur when an IndexedDB index is deleted while still in use by JavaScript code that is providing payload values to be stored. This results in a potentially exploitable crash.

A use-after-free vulnerability can occur when refresh driver timers are refreshed in some circumstances during shutdown when the timer is deleted while still in use. This results in a potentially exploitable crash.

Mozilla developers and community members Alex Gaynor, Boris Zbarsky, Christoph Diehl, Christian Holler, Jason Kratzer, Jed Davis, Tyson Smith, Bogdan Tara, Karl Tomlinson, Mats Palmgren, Nika Layzell, Ted Campbell, and Andrei Cristian Petcu reported memory safety bugs present in Firefox 61 and Firefox ESR 60.1. 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.

WebExtensions bundled with embedded experiments were not correctly checked for proper authorization. This allowed a malicious WebExtension to gain full browser permissions.

Windows 10 does not warn users before opening executable files with the SettingContent-ms extension even when they have been downloaded from the internet and have the "Mark of the Web." Without the warning, unsuspecting users unfamiliar with this new file type might run an unwanted executable. This also allows a WebExtension with the limited downloads.open permission to execute arbitrary code without user interaction on Windows 10 systems Note: this issue only affects Windows operating systems. Other operating systems are unaffected.