CVE-2020-28915

2020-11-1817:09:54

redhat.com

access.redhat.com

5.8 Medium

CVSS3

Attack Vector

PHYSICAL

Attack Complexity

LOW

Privileges Required

HIGH

User Interaction

NONE

Scope

UNCHANGED

Confidentiality Impact

LOW

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:P/AC:L/PR:H/UI:N/S:U/C:L/I:H/A:H

6.1 Medium

CVSS2

Access Vector

LOCAL

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

COMPLETE

AV:L/AC:L/Au:N/C:P/I:P/A:C

0.0004 Low

EPSS

Percentile

5.3%

JSON

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.

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