A flaw was found in Mozilla. The Mozilla Foundation Security Advisory describes the issue of when displaying the sender of an email, and the sender name contained the Braille Pattern Blank space character multiple times, Thunderbird displays all spaces. This flaw allows an attacker to send an email message with the attacker's digital signature that shows an arbitrary sender email address chosen by the attacker. If the sender's name started with a false email address, followed by many Braille space characters, the attacker's email address was not visible. Because Thunderbird compared the invisible sender address with the signature's email address, if Thunderbird accepted the signing key or certificate, the email was shown as having a valid digital signature.