CVE-2023-40546

Publication date 23 January 2024

Last updated 26 August 2025

Ubuntu priority

Medium

Why this priority?

Cvss 3 Severity Score

6.2 · Medium

Score breakdown

Description

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
shim-signed 26.04 LTS resolute
Fixed 1.58
25.10 questing
Fixed 1.58
25.04 plucky
Fixed 1.58
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
Fixed 1.51.4
20.04 LTS focal
Fixed 1.40.10
18.04 LTS bionic Ignored end of standard support
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Ignored end of standard support
shim 26.04 LTS resolute
Fixed 15.8-0ubuntu1
25.10 questing
Fixed 15.8-0ubuntu1
25.04 plucky
Fixed 15.8-0ubuntu1
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
Fixed 15.8-0ubuntu1
20.04 LTS focal
Fixed 15.8-0ubuntu1
18.04 LTS bionic Ignored end of standard support
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Ignored end of standard support
secureboot-db 26.04 LTS resolute
Not affected
25.10 questing
Not affected
25.04 plucky
Not affected
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

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

References

Other references

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