Mozilla Firefox ESR 78.14, Mozilla Firefox ESR 91.1, Mozilla Thunderbird 78.14, Mozilla Thunderbird 91.1: Mozilla developers Tyson Smith, Christian Holler, and Gabriele Svelto reported memory safety bugs present in Firefox 91 and Firefox ESR 91.0. 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.