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CVE-2022-3775

Published: 19 December 2022

When rendering certain unicode sequences, grub2's font code doesn't proper validate if the informed glyph's width and height is constrained within bitmap size. As consequence an attacker can craft an input which will lead to a out-of-bounds write into grub2's heap, leading to memory corruption and availability issues. Although complex, arbitrary code execution could not be discarded.

Notes

AuthorNote
eslerm
grub2-unsigned contains Secure Boot security fixes
the grub2 package unlikely affects Ubuntu's Secure Boot
grub2 and grub2-unsigned should have same major version
Ubuntu Secure Boot and ESM do not cover i386
trusty's GA kernel cannot handle new versions of grub
eslerm
Note that key revocation is required to protect against evil housekeeper attacks (such as BlackLotus)

Priority

Medium

Cvss 3 Severity Score

7.1

Score breakdown

Status

Package Release Status
grub2-unsigned
Launchpad, Ubuntu, Debian
xenial Needs triage

lunar
Released (2.06-2ubuntu15)
upstream Needs triage

trusty Does not exist

bionic
Released (2.06-2ubuntu14.1)
kinetic Ignored
(end of life)
focal
Released (2.06-2ubuntu14)
jammy
Released (2.06-2ubuntu14)
mantic Not vulnerable
(2.12~rc1-10ubuntu4)
grub2-signed
Launchpad, Ubuntu, Debian
trusty Needs triage

xenial Needs triage

upstream Needs triage

bionic
Released (1.187.3~18.04.1)
kinetic Ignored
(end of life)
lunar Not vulnerable
(1.192)
mantic Not vulnerable
(1.193)
focal
Released (1.187.3~20.04.1)
jammy
Released (1.187.3~22.04.1)
grub2
Launchpad, Ubuntu, Debian
jammy Not vulnerable
(does not affect Secure Boot)
upstream
Released (2.06-5)
lunar Not vulnerable
(does not affect Secure Boot)
mantic Not vulnerable
(does not affect Secure Boot)
bionic Not vulnerable
(does not affect Secure Boot)
focal Not vulnerable
(does not affect Secure Boot)
kinetic Not vulnerable
(does not affect Secure Boot)
trusty Not vulnerable
(does not affect Secure Boot)
xenial Not vulnerable
(does not affect Secure Boot)

Severity score breakdown

Parameter Value
Base score 7.1
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H