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CVE-2023-4692

Published: 3 October 2023

An out-of-bounds write flaw was found in grub2's NTFS filesystem driver. This issue may allow an attacker to present a specially crafted NTFS filesystem image, leading to grub's heap metadata corruption. In some circumstances, the attack may also corrupt the UEFI firmware heap metadata. As a result, arbitrary code execution and secure boot protection bypass may be achieved.

From the Ubuntu Security Team

It was discovered that a specially crafted file system image could cause a heap-based out-of-bounds write. An attacker could potentially use this to perform arbitrary code execution bypass and bypass secure boot protections.

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
eslerm
Ubuntu Secure Boot and ESM do not cover i386 trusty's GA kernel cannot handle new versions of grub Note that key revocation is required to protect against evil housekeeper attacks (such as BlackLotus)
eslerm
CWE-122

Priority

Medium

Cvss 3 Severity Score

7.8

Score breakdown

Status

Package Release Status
grub2
Launchpad, Ubuntu, Debian
bionic Ignored
(does not impact secure boot)
focal Ignored
(does not impact secure boot)
jammy Ignored
(does not impact secure boot)
upstream
Released (2.12~rc1-11)
mantic Ignored
(does not impact secure boot)
lunar Ignored
(does not impact secure boot)
trusty Ignored
(update incompatible with kernel)
xenial Ignored
(does not impact secure boot)
grub2-unsigned
Launchpad, Ubuntu, Debian
trusty Ignored
(end of standard support)
xenial Needs triage

bionic Needs triage

upstream Needs triage

focal
Released (2.06-2ubuntu14.4)
jammy
Released (2.06-2ubuntu14.4)
lunar
Released (2.06-2ubuntu17.2)
mantic Needs triage

grub2-signed
Launchpad, Ubuntu, Debian
trusty Ignored
(update incompatible with kernel)
xenial Needs triage

bionic Needs triage

upstream Needs triage

focal
Released (1.187.6~20.04.1)
jammy
Released (1.187.6)
lunar
Released (1.193.2)
mantic Needs triage

Severity score breakdown

Parameter Value
Base score 7.8
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H