CVE-2021-33656
kernel: when setting font with malicious data by ioctl PIO_FONT, kernel will write memory out of bounds
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · January 5, 2021
Updated · June 28, 2026
Description
An out-of-bounds write flaw was found in the Linux kernel’s console driver functionality in the way a user triggers the ioctl PIO_FONT with malicious data. This flaw allows a local user to crash or potentially escalate their privileges on the system.
Statement
This flaw is rated as a having Moderate impact, because only local user with the access to the VGA device can trigger it.
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
Mitigation for this issue is either not available or the currently available options don't meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.
CVSS / CWE
CVSS 3.1 · 6.8CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CWE-787 · Out-of-bounds Write