CVE-2020-28915
kernel: out-of-bounds read in fbcon_get_font function
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · November 16, 2020
Updated · June 28, 2026
Description
An out-of-bounds (OOB) memory access flaw was found in fbcon_get_font() in drivers/video/fbdev/core/fbcon.c in fbcon driver module in the Linux kernel. A bound check failure allows a local attacker with special user privilege to gain access to out-of-bounds memory, leading to a system crash or a leak of internal kernel information. The highest threat from this vulnerability is to integrity and system availability.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
Add 'nomodeset' option as kernel boot parameter to disable frame buffering (edit /etc/default/grub, and run 'grub2-mkconfig -o /boot/grub2/grub.cfg' and reboot).
# cat /proc/cmdline
BOOT_IMAGE=(hd0,msdos1)/vmlinuz-4.18.0-147.el8.x86_64 root=/dev/mapper/rhel_rhel8u2--1-root ro crashkernel=auto resume=/dev/mapper/rhel_rhel8u2--1-swap rd.lvm.lv=rhel_rhel8u2-1/root rd.lvm.lv=rhel_rhel8u2-1/swap nomodeset
# ls -l /dev/fb*
ls: cannot access '/dev/fb*': No such file or directory
CVSS / CWE
CVSS 3.1 · 5.8CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:H
CWE-125 · Out-of-bounds Read