This is a short announcement for all security researchers working on Firefox that use our pre-built AddressSanitzer (ASan) builds. Until recently, you could download these ASan builds from our FTP servers. Due to changes to our internal build infrastructure, these builds are no longer available from the usual location. Instead, they are available on a build system called TaskCluster. Most people just need the latest available build for testing purposes. Fortunately, this is easy to get:

Direct Download for Latest Firefox AddressSanitizer Build

For more advanced queries, TaskCluster offers a public API that can be used to interact with the system (e.g. to retrieve past builds). More information is available in the documentation.