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CVE-2023-40549

Published: 23 January 2024

An out-of-bounds read flaw was found in Shim due to the lack of proper boundary verification during the load of a PE binary. This flaw allows an attacker to load a crafted PE binary, triggering the issue and crashing Shim, resulting in a denial of service.

Notes

AuthorNote
eslerm
UEFI Security Response Team states that dbx update is not needed
secureboot-db should only ever be updated after shim
secureboot-db is not updated on ESM releases as doing so would
revoke install media keys Note that key revocation is required to
protect against evil housekeeper attacks (such as BlackLotus)

Priority

Medium

Cvss 3 Severity Score

5.5

Score breakdown

Status

Package Release Status
secureboot-db
Launchpad, Ubuntu, Debian
bionic Not vulnerable
(sbat only update)
focal Not vulnerable
(sbat only update)
jammy Not vulnerable
(sbat only update)
lunar Ignored
(end of life, was needs-triage)
mantic Not vulnerable
(sbat only update)
noble Not vulnerable
(sbat only update)
trusty Not vulnerable
(sbat only update)
upstream Not vulnerable
(sbat only update)
xenial Not vulnerable
(sbat only update)
shim
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Needed

jammy Needed

lunar Ignored
(end of life, was needs-triage)
mantic Ignored
(end of life, was needed)
noble
Released (15.8-0ubuntu1)
trusty Ignored
(install media keys will never be revoked)
upstream Needs triage

xenial Ignored
(install media keys will never be revoked)
Patches:
upstream: https://github.com/rhboot/shim/commit/afdc5039de0a4a3a40162a32daa070f94a883f09
shim-signed
Launchpad, Ubuntu, Debian
bionic Needs triage

focal Needed

jammy Needed

lunar Ignored
(end of life, was needs-triage)
mantic Ignored
(end of life, was needed)
noble
Released (15.8)
trusty Ignored
(install media keys will never be revoked)
upstream Needs triage

xenial Ignored
(install media keys will never be revoked)

Severity score breakdown

Parameter Value
Base score 5.5
Attack vector Local
Attack complexity Low
Privileges required Low
User interaction None
Scope Unchanged
Confidentiality None
Integrity impact None
Availability impact High
Vector CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H