Mozilla Firefox 87, Mozilla Firefox ESR 78.9 and Mozilla Thunderbird 78.9: Mozilla developers and community members Matthew Gregan, Tyson Smith, Julien Wajsberg, and Alexis Beingessner reported memory safety bugs present in Firefox 86 and Firefox ESR 78.8. 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.