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CVE-2023-40546

Published: 23 January 2024

A flaw was found in Shim when an error happened while creating a new ESL variable. If Shim fails to create the new variable, it tries to print an error message to the user; however, the number of parameters used by the logging function doesn't match the format string used by it, leading to a crash under certain circumstances.

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/66e6579dbf921152f647a0c16da1d3b2f40861ca
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