CVE-2023-39950
MediumCVSS 6.1Exploitation Probability (EPSS)
Low risk30th percentile - higher than 30% of all known CVEs
Summary
The vulnerability in efibootguard arises from insufficient validation and sanitization of input from untrusted bootloader environment files, which can lead to crashes and potential code injections. This issue occurs when attempting to modify a manipulated environment, particularly user variables.
Risk Assessment
The organization may be exposed to system crashes and the possibility of malicious code injection, which could lead to data loss or system takeover. Unpatched components may pose a significant security threat.
Recommendation
It is recommended to update the efibootguard library and tools to version v0.15, which contains patches to sanitize and validate the bootloader environment. Avoid modifying user variables if using an unpatched version of efibootguard.
Original NVD description (English source)
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.