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CVE-2023-39950

Insufficient input validation in efibootguard

6.1 MediumFix available

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.

Attack profile

How easy it is to exploit

Attack vector
Physical
Complexity
Low
Privileges needed
None
User interaction
None

What an attacker can affect

Confidentiality
None
Integrity
High
Availability
Low

Exploit likelihood

0.42%Up 0.4 points since Aug 15, 2023
90%50%10%1%

What each source reports

CVE List Score used 6.1

Insufficient input validation in efibootguard

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.

Record
CVE-2023-39950
CVSS 3.1
6.1 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Weakness
CWE-20
Updated
2026-11-02
EUVDEUVD-2023-43648 6.1

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.

Record
EUVD-2023-43648
CVSS 3.1
6.1 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Updated
2026-11-03
NVD 6.1

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.

Record
CVE-2023-39950
CVSS 3.1
6.1 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
CVSS 3.1
5.2 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
Weakness
CWE-20
Updated
2026-11-02
OSV 6.1

Insufficient input validation in efibootguard

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.

Record
CVE-2023-39950
CVSS 3.1
6.1 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
Weakness
CWE-20
Updated
2026-11-02
OSVDEBIAN-CVE-2023-39950 5.2

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.

Record
DEBIAN-CVE-2023-39950
CVSS 3.1
5.2 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
Updated
2026-11-02
OSVUBUNTU-CVE-2023-39950 6.1

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.

Record
UBUNTU-CVE-2023-39950
CVSS 3.1
6.1 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
CVSS 3.1
5.2 MediumCVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:L
Updated
2026-11-02

Affected products

Affected packages

Affected packages
PackageAffectedFixed
efibootguard
Debian:12
before 0.13-2+deb12u1, plus listed versions
0.13-20.13-2+deb12u1~bpo11+1
0.13-2+deb12u1
efibootguard
Debian:13
before 0.15-1
0.15-1
efibootguard
Debian:14
before 0.15-1
0.15-1
efibootguard
Ubuntu:24.04:LTS
All versions, plus listed versions
0.15-10.16-10.16-2
None known
efibootguard
Ubuntu:25.10
All versions, plus listed versions
0.19-1
None known
efibootguard
Ubuntu:26.10
All versions, plus listed versions
0.19-10.22-2ubuntu1
None known
efibootguard
Ubuntu:26.04:LTS
All versions, plus listed versions
0.19-1
None known

History

History
RecordedChangedSources
aliases, publishedEUVD
first indexedCVE List, NVD, OSV

Dates are when Every CVE recorded each change. Upstream dates may differ.

In short

CVE-2023-39950 is a medium vulnerability (CVSS 6.1) in Siemens Efibootguard, published August 14, 2023. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 0.42%, the 36th percentile. Fixed in efibootguard 0.13-2+deb12u1.

References

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