PublicDateAtUSN: 2021-03-02 18:00:00 UTC
Candidate: CVE-2021-20233
CRD: 2021-03-02 18:00:00 UTC
PublicDate: 2021-03-03 17:15:00 UTC
References: 
 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-20233
 https://ubuntu.com/security/notices/USN-4992-1
Description:
 A flaw was found in grub2 in versions prior to 2.06. Setparam_prefix() in
 the menu rendering code performs a length calculation on the assumption
 that expressing a quoted single quote will require 3 characters, while it
 actually requires 4 characters which allows an attacker to corrupt memory
 by one byte for each quote in the input. The highest threat from this
 vulnerability is to data confidentiality and integrity as well as system
 availability.
Ubuntu-Description: 
 It was discovered that the menu rendering implementation in GRUB 2 did
 not properly calculate the amount of memory needed in some situations,
 leading to out-of-bounds writes. A local attacker could use this
 to execute arbitrary code and bypass UEFI Secure Boot restrictions.
Notes: 
 sbeattie| grub2-unsigned will contain fixes and supersede grub2, which
  will contain only BIOS grub bits.
Mitigation: 
Bugs: 
Priority: medium
Discovered-by:
Assigned-to: 
CVSS:
 nvd: CVSS:3.1/AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H [8.2 HIGH]


Patches_grub2-unsigned:
upstream_grub2-unsigned: needs-triage
precise/esm_grub2-unsigned: ignored (end of ESM support, was needs-triage)
trusty_grub2-unsigned: ignored (out of standard support)
trusty/esm_grub2-unsigned: needs-triage
xenial_grub2-unsigned: pending (2.04-1ubuntu42)
esm-infra/xenial_grub2-unsigned: pending (2.04-1ubuntu42)
bionic_grub2-unsigned: released (2.04-1ubuntu44.1.2)
focal_grub2-unsigned: released (2.04-1ubuntu44.2)
groovy_grub2-unsigned: released (2.04-1ubuntu44.2)
hirsute_grub2-unsigned: released (2.04-1ubuntu42)
impish_grub2-unsigned: released (2.04-1ubuntu45)
jammy_grub2-unsigned: released (2.04-1ubuntu45)
devel_grub2-unsigned: released (2.04-1ubuntu45)

Patches_grub2-signed:
upstream_grub2-signed: needs-triage
precise/esm_grub2-signed: DNE
trusty_grub2-signed: ignored (out of standard support)
trusty/esm_grub2-signed: needs-triage
xenial_grub2-signed: ignored (end of standard support, was needs-triage)
esm-infra/xenial_grub2-signed: pending (1.164)
bionic_grub2-signed: released (1.167~18.04.5)
focal_grub2-signed: released (1.167.2)
groovy_grub2-signed: released (1.167.2)
hirsute_grub2-signed: released (1.164)
impish_grub2-signed: released (1.169)
jammy_grub2-signed: released (1.169)
devel_grub2-signed: released (1.169)