CVE-2023-39950
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.
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
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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L - CVSS 3.1
- 5.2 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS: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 Medium
CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L - CVSS 3.1
- 5.2 Medium
CVSS: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
| Package | Affected | Fixed |
|---|---|---|
efibootguardDebian:12 |
before 0.13-2+deb12u1, plus listed versions 0.13-20.13-2+deb12u1~bpo11+1 |
0.13-2+deb12u1 |
efibootguardDebian:13 |
before 0.15-1 | 0.15-1 |
efibootguardDebian:14 |
before 0.15-1 | 0.15-1 |
efibootguardUbuntu:24.04:LTS |
All versions, plus listed versions 0.15-10.16-10.16-2 |
None known |
efibootguardUbuntu:25.10 |
All versions, plus listed versions 0.19-1 |
None known |
efibootguardUbuntu:26.10 |
All versions, plus listed versions 0.19-10.22-2ubuntu1 |
None known |
efibootguardUbuntu:26.04:LTS |
All versions, plus listed versions 0.19-1 |
None known |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases, published | EUVD | |
| first indexed | CVE 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
github.com/siemens/efibootguard/security/advisories/GHSA-j6pp-7g99-24m7
github.com/siemens/efibootguard/blob/master/docs/API.md
github.com/siemens/efibootguard/blob/master/docs/TOOLS.md
github.com/siemens/efibootguard/tags
github.com/CVEProject/cvelistV5/tree/main/cves/2023/39xxx/CVE-2023-39950.json
nvd.nist.gov/vuln/detail/CVE-2023-39950