Debian: DSA-4287-1 Moderate: Firefox-ESR Memory Safety Issues

Several security issues have been found in the Mozilla Firefox web
browser: Multiple memory safety errors and use-after-frees may lead to
the execution of arbitrary code or denial of service.

Debian follows the extended support releases (ESR) of Firefox. Support
for the 52.x series has ended, so starting with this update we're now
following the 60.x releases.

Between 52.x and 60.x, Firefox has undergone significant internal
updates, which makes it incompatible with a number of extensions. For
more information please refer to
https://www.firefox.com/en-US/firefox/60.0esr/releasenotes/?redirect_source=mozilla-org

In addition, the new Firefox packages require Rust to build. A
compatible Rust toolchain has been backported to Debian stretch, but is
not available for all architectures which previously supported the
purely C++-based Firefox packages. Thus, the new Firefox packages
don't support the armel, armhf, mips, mips64el and mipsel architectures
at this point.

For the stable distribution (stretch),...