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CVE-2023-40546

Publication date 23 January 2024

Last updated 24 July 2024

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

5.5 · Medium

Score breakdown

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.

Read the notes from the security team

Status

Package Ubuntu Release Status
secureboot-db 24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar Ignored end of life, was needs-triage
22.04 LTS jammy
Not affected
20.04 LTS focal
Not affected
18.04 LTS bionic
Not affected
16.04 LTS xenial
Not affected
14.04 LTS trusty
Not affected
shim 24.10 oracular
Fixed 15.8-0ubuntu1
24.04 LTS noble
Fixed 15.8-0ubuntu1
23.10 mantic Ignored end of life, was needed
23.04 lunar Ignored end of life, was needs-triage
22.04 LTS jammy
Vulnerable
20.04 LTS focal
Vulnerable
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial Ignored install media keys will never be revoked
14.04 LTS trusty Ignored install media keys will never be revoked
shim-signed 24.10 oracular
Fixed 1.58
24.04 LTS noble
Fixed 1.58
23.10 mantic Ignored end of life, was needed
23.04 lunar Ignored end of life, was needs-triage
22.04 LTS jammy
Vulnerable
20.04 LTS focal
Vulnerable
18.04 LTS bionic
Needs evaluation
16.04 LTS xenial Ignored install media keys will never be revoked
14.04 LTS trusty Ignored install media keys will never be revoked

Notes

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)

Patch details

For informational purposes only. We recommend not to cherry-pick updates. How can I get the fixes?

Package Patch details
shim

Severity score breakdown

Parameter Value
Base score 5.5 · Medium
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