In GnuPG before 2.4.9, armor_filter in g10/armor.c has two increments of an index variable where one is intended, leading to an out-of-bounds write for crafted input. (For ExtendedLTS, 2.2.51 and later are fixed versions.)
Exploitability
AV:LAC:HPR:NUI:NScope
S:CImpact
C:HI:HA:N7.8/CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:NOther