Memory safety bugs present in Firefox 138 and Thunderbird 138. 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. This vulnerability affects Firefox < 139 and Thunderbird < 139.
In certain cases, SNI could have been sent unencrypted even when encrypted DNS was enabled. This vulnerability affects Firefox < 139 and Thunderbird < 139.
Previewing a response in Devtools ignored CSP headers, which could have allowed content injection attacks. This vulnerability affects Firefox < 139 and Thunderbird < 139.
A race condition existed in nsHttpTransaction that could have been exploited to cause memory corruption, potentially leading to an exploitable condition. This vulnerability affects Firefox < 137.0.2.