The ext4_valid_block_bitmap function in fs/ext4/balloc.c in the Linux kernel through 4.15.15 allows attackers to cause a denial of service (out-of-bounds read and system crash) via a crafted ext4 image because balloc.c and ialloc.c do not validate bitmap block numbers.
Exploitability
AV:LAC:LPR:NUI:RScope
S:UImpact
C:NI:NA:H5.5/CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H