Your submission was sent successfully! Close

You have successfully unsubscribed! Close

Thank you for signing up for our newsletter!
In these regular emails you will find the latest updates about Ubuntu and upcoming events where you can meet our team.Close

CVE-2023-40547

Published: 23 January 2024

A remote code execution vulnerability was found in Shim. The Shim boot support trusts attacker-controlled values when parsing an HTTP response. This flaw allows an attacker to craft a specific malicious HTTP request, leading to a completely controlled out-of-bounds write primitive and complete system compromise. This flaw is only exploitable during the early boot phase, an attacker needs to perform a Man-in-the-Middle or compromise the boot server to be able to exploit this vulnerability successfully.

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

9.0

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/0226b56513b2b8bd5fd281bce77c40c9bf07c66d
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 9.0
Attack vector Network
Attack complexity High
Privileges required None
User interaction None
Scope Changed
Confidentiality High
Integrity impact High
Availability impact High
Vector CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:C/C:H/I:H/A:H