Mozilla has fixed two security issues in this update.
Previous Thunderbird versions did not percent-encode spaces and double-quotes in URIs handed off to external programs for handling, which can cause the receiving program to mistakenly interpret a single URI as multiple arguments. This bug is fixed in Thunderbird 188.8.131.52.
Privilege escalation through chrome-loaded about:blank windows issue also has been fixed in Thunderbird 184.108.40.206.
Download Thunderbird 220.127.116.11