[MFSA-2020-13] Security Vulnerabilities fixed in Firefox ESR 68.7

CVE-2020-6821: Uninitialized memory could be read when using the WebGL copyTexSubImage method (high)
When reading from areas partially or fully outside the source resource with WebGL's <code>copyTexSubImage</code> method, the specification requires the returned values be zero. Previously, this memory was uninitialized, leading to potentially sensitive data disclosure.

CVE-2020-6822: Out of bounds write in GMPDecodeData when processing large images (moderate)
On 32-bit builds, an out of bounds write could have occurred when processing an image larger than 4 GB in <code>GMPDecodeData</code>. It is possible that with enough effort this could have been exploited to run arbitrary code.

CVE-2020-6825: Memory safety bugs fixed in Firefox 75 and Firefox ESR 68.7 (high)
Mozilla developers Tyson Smith and Christian Holler reported memory safety bugs present in Firefox 74 and Firefox ESR 68.6. Some of these bugs showed evidence of memory corruption and we presume that with enough effort some of these could have been exploited to run arbitrary code.

CVE-2020-6827: Custom Tabs in Firefox for Android could have the URI spoofed (high)
When following a link that opened an intent://-schemed URL, causing a custom tab to be opened, Firefox for Android could be tricked into displaying the incorrect URI.
Note: This issue only affects Firefox for Android. Other operating systems are unaffected.

CVE-2020-6828: Preference overwrite via crafted Intent from malicious Android application (high)
A malicious Android application could craft an Intent that would have been processed by Firefox for Android and potentially result in a file overwrite in the user's profile directory. One exploitation vector for this would be to supply a user.js file providing arbitrary malicious preference values. Control of arbitrary preferences can lead to sufficient compromise such that it is generally equivalent to arbitrary code execution.
Note: This issue only affects Firefox for Android. Other operating systems are unaffected.