Mozilla developers and community members reported memory safety bugs present in Firefox 67 and Firefox ESR 60.7. 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 ESR < 60.8, Firefox < 68, and Thunderbird < 60.8.

Insufficient vetting of parameters passed with the Prompt:Open IPC message between child and parent processes can result in the non-sandboxed parent process opening web content chosen by a compromised child process. When combined with additional vulnerabilities this could result in executing arbitrary code on the user's computer. This vulnerability affects Firefox ESR < 60.7.2, Firefox < 67.0.4, and Thunderbird < 60.7.2.

A type confusion vulnerability can occur when manipulating JavaScript objects due to issues in Array.pop. This can allow for an exploitable crash. We are aware of targeted attacks in the wild abusing this flaw. This vulnerability affects Firefox ESR < 60.7.1, Firefox < 67.0.3, and Thunderbird < 60.7.2.

A hyperlink using protocols associated with Internet Explorer, such as IE.HTTP:, can be used to open local files at a known location with Internet Explorer if a user approves execution when prompted. *Note: this issue only occurs on Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox < 67.0.2.

The default webcal: protocol handler will load a web site vulnerable to cross-site scripting (XSS) attacks. This default was left in place as a legacy feature and has now been removed. *Note: this issue only affects users with an account on the vulnerable service. Other users are unaffected.*. This vulnerability affects Firefox < 67.

A hyperlink using the res: protocol can be used to open local files at a known location in Internet Explorer if a user approves execution when prompted. *Note: this issue only occurs on Windows. Other operating systems are unaffected.*. This vulnerability affects Firefox < 67.

A malicious page can briefly cause the wrong name to be highlighted as the domain name in the addressbar during page navigations. This could result in user confusion of which site is currently loaded for spoofing attacks. This vulnerability affects Firefox < 67.

If a crafted hyperlink is dragged and dropped to the bookmark bar or sidebar and the resulting bookmark is subsequently dragged and dropped into the web content area, an arbitrary query of a user's browser history can be run and transmitted to the content page via drop event data. This allows for the theft of browser history by a malicious site. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

If the ALT and "a" keys are pressed when users receive an extension installation prompt, the extension will be installed without the install prompt delay that keeps the prompt visible in order for users to accept or decline the installation. A malicious web page could use this with spoofing on the page to trick users into installing a malicious extension. This vulnerability affects Firefox < 67.

Files with the .JNLP extension used for "Java web start" applications are not treated as executable content for download prompts even though they can be executed if Java is installed on the local system. This could allow users to mistakenly launch an executable binary locally. This vulnerability affects Firefox < 67.

A custom cursor defined by scripting on a site can position itself over the addressbar to spoof the actual cursor when it should not be allowed outside of the primary web content area. This could be used by a malicious site to trick users into clicking on permission prompts, doorhanger notifications, or other buttons inadvertently if the location is spoofed over the user interface. This vulnerability affects Firefox < 67.

A vulnerability exists in the Windows sandbox where an uninitialized value in memory can be leaked to a renderer from a broker when making a call to access an otherwise unavailable file. This results in the potential leaking of information stored at that memory location. *Note: this issue only occurs on Windows. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

The bufferdata function in WebGL is vulnerable to a buffer overflow with specific graphics drivers on Linux. This could result in malicious content freezing a tab or triggering a potentially exploitable crash. *Note: this issue only occurs on Linux. Other operating systems are unaffected.*. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

A use-after-free vulnerability can occur when listeners are removed from the event listener manager while still in use, resulting in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

A use-after-free vulnerability can occur when working with XMLHttpRequest (XHR) in an event loop, causing the XHR main thread to be called after it has been freed. This results in a potentially exploitable crash. This vulnerability affects Thunderbird < 60.7, Firefox < 67, and Firefox ESR < 60.7.

Incorrect handling of __proto__ mutations may lead to type confusion in IonMonkey JIT code and can be leveraged for arbitrary memory read and write. This vulnerability affects Firefox < 66.0.1, Firefox ESR < 60.6.1, and Thunderbird < 60.6.1.

Incorrect alias information in IonMonkey JIT compiler for Array.prototype.slice method may lead to missing bounds check and a buffer overflow. This vulnerability affects Firefox < 66.0.1, Firefox ESR < 60.6.1, and Thunderbird < 60.6.1.

If the source for resources on a page is through an FTP connection, it is possible to trigger a series of modal alert messages for these resources through invalid credentials or locations. These messages cannot be immediately dismissed, allowing for a denial of service (DOS) attack. This vulnerability affects Firefox < 66.

If WebRTC permission is requested from documents with data: or blob: URLs, the permission notifications do not properly display the originating domain. The notification states "Unknown origin" as the requestee, leading to user confusion about which site is asking for this permission. This vulnerability affects Firefox < 66.

When arbitrary text is sent over an FTP connection and a page reload is initiated, it is possible to create a modal alert message with this text as the content. This could potentially be used for social engineering attacks. This vulnerability affects Firefox < 66.