Text stolen from MITRE:
Double-free vulnerability in Mozilla Thunderbird before 18.104.22.168 and
SeaMonkey before 1.0.2 allows remote attackers to cause a denial of
service (hang) and possibly execute arbitrary code via a VCard that
contains invalid base64 characters.
Mozilla Firefox and Thunderbird before 22.214.171.124 allow remote attackers
to cause a denial of service (crash) and possibly execute arbitrary
code via (1) nested <option> tags in a select tag, (2) a
DOMNodeRemoved mutation event, (3) "Content-implemented tree views,"
(4) BoxObjects, (5) the XBL implementation, (6) an iframe that
attempts to remove itself, which leads to memory corruption.
These issues also affect RHEL2.1 and RHEL3
Integer overflow in Mozilla Firefox and Thunderbird before 126.96.36.199 allows remote
attackers to cause a denial of service (crash) and possibly execute arbitrary
code via "jsstr tagify," which leads to memory corruption.
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on the solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.