CVE-2022-50511: 
Linux Kernel vulnerability analysis and mitigation

CVE-2022-50511 is a vulnerability in the Linux kernel that was discovered and disclosed on October 7, 2025. The issue affects the font handling functionality in the Linux kernel's lib/fonts component, specifically related to undefined behavior in bit shift operations for the get_default_font function (NVD).

The vulnerability stems from shifting a signed 32-bit value by 31 bits, which results in undefined behavior. The issue manifests in lib/fonts/fonts.c:139:20 where a left shift of 1 by 31 places cannot be represented in the 'int' type. This triggers UBSAN (Undefined Behavior Sanitizer) warnings and can potentially crash under certain configurations during framebuffer/font selection, specifically during module initialization or fbcon startup (RedHat). The vulnerability has been assigned a CVSS v3.1 base score of 4.4 with vector CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:U/C:N/I:N/A:H.

The vulnerability can lead to system crashes under specific configurations during framebuffer or font selection operations. The impact is primarily limited to system availability, with no direct impact on confidentiality or integrity. The issue requires privileged or local operations for exploitation, specifically during module/driver initialization or framebuffer setup (RedHat).

The vulnerability has been fixed in various Linux distributions. Ubuntu has released patches for multiple versions, including fixes in version 5.15.0-69.76 for Ubuntu 22.04 LTS and 5.4.0-144.161 for Ubuntu 20.04 LTS (Ubuntu). Red Hat has addressed the issue in Red Hat Enterprise Linux 9 with kernel version 5.14.0-570.12.1.el9_6 (RedHat).