Security Vulnerabilities fixed in Firefox 78 — Mozilla

When %2F was present in a manifest URL, Firefox’s AppCache behavior may have become confused and allowed a manifest to be served from a subdirectory. This could cause the appcache to be used to service requests for the top level directory.
A VideoStreamEncoder may have been freed in a race condition with VideoBroadcaster::AddOrUpdateSink, resulting in a use-after-free, memory corruption, and a potentially exploitable crash.
Due to confusion about ValueTags on JavaScript Objects, an object may pass through the type barrier, resulting in memory corruption and a potentially exploitable crash.Note: this issue only affects Firefox on ARM64 platforms.
Manipulating individual parts of a URL object could have caused an out-of-bounds read, leaking process memory to malicious JavaScript.
When processing callbacks that occurred during window flushing in the parent process, the associated window may die; causing a use-after-free condition. This could have led to memory corruption and a potentially exploitable crash.
When trying to connect to a STUN server, a race condition could have caused a use-after-free of a pointer, leading to memory corruption and a potentially exploitable crash.
During RSA key generation, bignum implementations used a variation of the Binary Extended Euclidean Algorithm which entailed significantly input-dependent flow. This allowed an attacker able to perform electromagnetic-based side channel attacks to record traces leading to the recovery of the secret primes. We would like to thank Sohaib ul Hassan for contributing a fix for this issue as well.Note: An unmodified Firefox browser does not generate RSA keys in normal operation and is not affected, but products built on top of it might.
When performing add-on updates, certificate chains terminating in non-built-in-roots were rejected (even if they were legitimately added by an administrator.) This could have caused add-ons to become out-of-date silently without notification to the user.
In non-standard configurations, a JPEG image created by JavaScript could have caused an internal variable to overflow, resulting in an out of bounds write, memory corruption, and a potentially exploitable crash.
When the Windows DLL “webauthn.dll” was missing from the Operating System, and a malicious one was placed in a folder in the user’s %PATH%, Firefox may have loaded the DLL, leading to arbitrary code execution. Note: This issue only affects the Windows operating system; other operating systems are unaffected.
When constructing a permission prompt for WebRTC, a URI was supplied from the content process. This URI was untrusted, and could have been the URI of an origin that was previously granted permission; bypassing the prompt.
Due to confusion processing a hyphen character in Date.parse(), a one-byte out of bounds read could have occurred, leading to potential information disclosure.
Mozilla developers and community members Bob Clary, Benjamin Bouvier, Calixte Denizet, Christian Holler reported memory safety bugs present in Firefox 77. 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.