Staging Environment: Content and features may be unstable or change without notice.
Advisory details: ubuntu_osv / UBUNTU-CVE-2023-39950
Advisory ID ubuntu_osv/UBUNTU-CVE-2023-39950
Aliases CVE-2023-39950
Summary efibootguard is a simple UEFI boot loader with support for safely switching between current and updated partition sets. Insufficient or missing validation and sanitization of input from untrustworthy bootloader environment files can cause crashes and probably also code injections into `bg_setenv`) or programs using `libebgenv`. This is triggered when the affected components try to modify a manipulated environment, in particular its user variables. Furthermore, `bg_printenv` may crash over invalid read accesses or report invalid results. Not affected by this issue is EFI Boot Guard's bootloader EFI binary. EFI Boot Guard release v0.15 contains required patches to sanitize and validate the bootloader environment prior to processing it in userspace. Its library and tools should be updated, so should programs statically linked against it. An update of the bootloader EFI executable is not required. The only way to prevent the issue with an unpatched EFI Boot Guard version is to avoid accesses to user variables, specifically modifications to them.
Status Published
Exploitability 0.5
Weighted Severity 6.2
Risk 3.1
Affected and Fixed Packages Package Details
Introduced and Fixed Package Commit Patches Package Commit Patches Details
Weaknesses (0)
There are no known CWE.
System Score Found at
cvssv3.1 5.2 https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json
cvssv3.1 6.1 https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json
ubuntu-priority medium https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json
Reference id Reference type URL
https://github.com/siemens/efibootguard/commit/53dee61dc8b3a83c882e4bc9a0cfe7d6d73610c4
https://github.com/siemens/efibootguard/commit/965d65c5751898c4bb094ef191b7387819423414
https://ubuntu.com/security/CVE-2023-39950
https://www.cve.org/CVERecord?id=CVE-2023-39950
API.md Other https://github.com/siemens/efibootguard/blob/master/docs/API.md
GHSA-j6pp-7g99-24m7 Other https://github.com/siemens/efibootguard/security/advisories/GHSA-j6pp-7g99-24m7
tags Other https://github.com/siemens/efibootguard/tags
TOOLS.md Other https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md
TOOLS.md#setting-user-variables Other https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md#setting-user-variables
No exploits are available.

No EPSS data available for this advisory.

Patch URL
There are no known patches.
Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L Found at https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none
Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L Found at https://github.com/canonical/ubuntu-security-notices/blob/main/osv/cve/2023/UBUNTU-CVE-2023-39950.json
Attack Vector (AV) Attack Complexity (AC) Privileges Required (PR) User Interaction (UI) Scope (S) Confidentiality Impact (C) Integrity Impact (I) Availability Impact (A)

network

adjacent_network

local

physical

low

high

none

low

high

none

required

unchanged

changed

high

low

none

high

low

none

high

low

none

There are no SSVC decisions available.