When a user clicked on an FTP URL containing encoded newline characters (%0A and %0D), the newlines would have been interpreted as such and allowed arbitrary commands to be sent to the FTP server. This vulnerability affects Firefox ESR < 78.10, Thunderbird < 78.10, and Firefox < 88.
78.10.0esr-11:78.10.0-1Exploitability
AV:NAC:LPR:NUI:RScope
S:UImpact
C:HI:HA:HCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H