A flaw during verification of certain S/MIME signatures causes emails...

Vulnerability Description

A flaw during verification of certain S/MIME signatures causes emails to be shown in Thunderbird as having a valid digital signature, even if the shown message contents aren't covered by the signature. The flaw allows an attacker to reuse a valid S/MIME signature to craft an email message with arbitrary content. This vulnerability affects Thunderbird < 60.5.1.

References

• http://lists.opensuse.org/opensuse-security-announce/2019-04/msg00043.html
• https://www.mozilla.org/security/advisories/mfsa2019-06/
• https://bugzilla.mozilla.org/show_bug.cgi?id=1507218
• http://www.openwall.com/lists/oss-security/2019/04/30/4
• http://seclists.org/fulldisclosure/2019/Apr/38
• http://packetstormsecurity.com/files/152703/Johnny-You-Are-Fired.html
• https://access.redhat.com/errata/RHSA-2019:1144
• https://github.com/RUB-NDS/Johnny-You-Are-Fired
• https://github.com/RUB-NDS/Johnny-You-Are-Fired/blob/master/paper/johnny-fired.pdf