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CVE-2020-14311

Published: 29 July 2020

There is an issue with grub2 before version 2.06 while handling symlink on ext filesystems. A filesystem containing a symbolic link with an inode size of UINT32_MAX causes an arithmetic overflow leading to a zero-sized memory allocation with subsequent heap-based buffer overflow.

From the Ubuntu Security Team

Chris Coulson discovered that multiple integer overflows existed in GRUB2 when handling certain filesystems, font files or PNG images, leading to heap-based buffer overflows. A local attacker could use these to execute arbitrary code and bypass UEFI Secure Boot restrictions.

Notes

AuthorNote
alexmurray
grub2-signed is not supported in Ubuntu 12.04 ESM (precise/esm) and so marking the priority for grub2 in this release as low

Priority

High

Cvss 3 Severity Score

5.7

Score breakdown

Status

Package Release Status
grub2
Launchpad, Ubuntu, Debian
bionic
Released (2.02-2ubuntu8.16)
focal
Released (2.04-1ubuntu26.1)
groovy Not vulnerable
(2.04-1ubuntu26.1)
hirsute Not vulnerable
(2.04-1ubuntu26.1)
jammy Not vulnerable
(2.06-2ubuntu7)
kinetic Not vulnerable
(2.06-2ubuntu12)
lunar Not vulnerable
(2.06-2ubuntu16)
mantic Not vulnerable
(2.06-2ubuntu18)
trusty
Released (2.02~beta2-9ubuntu1.20)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
upstream Needs triage

xenial
Released (2.02~beta2-36ubuntu3.26)
grub2-signed
Launchpad, Ubuntu, Debian
bionic
Released (1.93.18)
eoan Ignored
(end of life)
focal
Released (1.142.3)
groovy Not vulnerable
(1.147)
hirsute Not vulnerable
(1.147)
jammy Not vulnerable
(1.182~22.04.1)
kinetic Not vulnerable
(1.185)
lunar Not vulnerable
(1.192)
mantic Not vulnerable
(1.193)
trusty
Released (1.34.22)
Available with Ubuntu Pro or Ubuntu Pro (Infra-only)
upstream Needs triage

xenial
Released (1.66.26)
grub2-unsigned
Launchpad, Ubuntu, Debian
bionic
Released (2.04-1ubuntu47.4)
focal
Released (2.04-1ubuntu47.4)
jammy Not vulnerable
(2.06-2ubuntu7)
kinetic Not vulnerable
(2.06-2ubuntu12)
lunar Not vulnerable
(2.06-2ubuntu16)
mantic Not vulnerable
(2.06-2ubuntu17)
trusty Does not exist

upstream Needs triage

xenial Needed

Severity score breakdown

Parameter Value
Base score 5.7
Attack vector Local
Attack complexity High
Privileges required High
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:N/I:H/A:H