Vulnerability · Published Aug 14, 2023 · Assigned by GitHub_M
CVE-2023-39950Insufficient input validation in efibootguard
Medium 6.1
In plain English
A medium-severity improper input validation in efibootguard from siemens. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
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.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian:12 | efibootguard | 0.13-2+deb12u1 | DEBIAN-CVE-2023-39950 |
| Debian:13 | efibootguard | 0.15-1 | DEBIAN-CVE-2023-39950 |
| Debian:14 | efibootguard | 0.15-1 | DEBIAN-CVE-2023-39950 |
| Ubuntu:24.04:LTS | efibootguard | no fix listed | UBUNTU-CVE-2023-39950 |
| Ubuntu:25.10 | efibootguard | no fix listed | UBUNTU-CVE-2023-39950 |
| Ubuntu:26.04:LTS | efibootguard | no fix listed | UBUNTU-CVE-2023-39950 |
| Ubuntu:26.10 | efibootguard | no fix listed | UBUNTU-CVE-2023-39950 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| siemens | efibootguard | < 0.15 |
Weakness: CWE-20 · Vector: CVSS:3.1/AV:P/AC:L/PR:N/UI:N/S:C/C:N/I:H/A:L
References
- https://github.com/siemens/efibootguard/security/advisories/GHSA-j6pp-7g99-24m7 x_refsource_CONFIRM
- https://github.com/siemens/efibootguard/blob/master/docs/API.md x_refsource_MISC
- https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md x_refsource_MISC
- https://github.com/siemens/efibootguard/blob/master/docs/TOOLS.md#setting-user-variables x_refsource_MISC
- https://github.com/siemens/efibootguard/tags x_refsource_MISC