Exim 4 before 4.94.2 allows Integer Overflow to Buffer Overflow because get_stdinput allows unbounded reads that are accompanied by unbounded increases in a certain size variable. NOTE: exploitation may be impractical because of the execution time needed to overflow (multiple days).
Exploitability
AV:LAC:LPR:LUI:NScope
S:UImpact
C:HI:HA:H7.8/CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H