Fix EFAIL

Originally created by @segfault on #15602 (Redmine)

This is about http://efail.de, a vulnerability in multiple email clients, including Thunderbird + Enigmail, which allows exfiltrating plaintext of GPG encrypted emails.

What we know so far:

• The enigmail version we ship (1.9.9) seems to be affected, and there don’t seem to be any security patches to the Debian package after the 1.9.9 release.

• According to this, Thunderbird doesn’t have patches released yet

• We could be saved by Torbirdy, because, according to the EFAIL website, “the most prominent way of attacking EFAIL” uses HTML, and Torbirdy completely disables HTML.

Team: sajolida

Feature Branch: feature/15091-thunderbird-60

Attachments

• remote content.png

Related issues

• Related to #15657 (closed)
• Related to #15486 (closed)
• Related to #15661 (closed)
• Related to #15692 (closed)
• Related to #15658 (closed)
• Blocked by #15607 (closed)
• Blocks tails/accounting#15334
• Blocked by #15091 (closed)