A vulnerability was found in grub2 up to 2.04. It has been rated as critical. Affected by this issue is the function grub_script_function_create of the component Secure Boot. The manipulation with an unknown input leads to a race condition vulnerability. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. Impacted is confidentiality, integrity, and availability. CVE summarizes:

GRUB2 contains a race condition in grub_script_function_create() leading to a use-after-free vulnerability which can be triggered by redefining a function whilst the same function is already executing, leading to arbitrary code execution and secure boot restriction bypass. This issue affects GRUB2 version 2.04 and prior versions.

The weakness was shared 07/29/2020 (Website). The advisory is shared for download at lists.gnu.org. This vulnerability is handled as CVE-2020-15706 since 07/14/2020. The attack needs to be approached locally. Additional levels of successful authentication are needed for exploitation. There are known technical details, but no exploit is available.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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• grub2

Version

• 2.04

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• open-source

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