CVE-2025-61661
Description
A vulnerability has been identified in the GRUB (Grand Unified Bootloader) component. This flaw occurs because the bootloader mishandles string conversion when reading information from a USB device, allowing an attacker to exploit inconsistent length values. A local attacker can connect a maliciously configured USB device during the boot sequence to trigger this issue. A successful exploitation may lead GRUB to crash, leading to a Denial of Service. Data corruption may be also possible, although given the complexity of the exploit the impact is most likely limited.
Statement
This vulnerability was rated as having the impact of Moderate by the Red Hat Product Security Engineering team. To exploit this flaw the attacker needs to have physical access to the machine and connect a maliciously crafted USB device which will leverage the lack of string size validation to cause a out-of-bounds write when reading strings from it. Even though the existence of a possible out-of-bounds write, given the complexity of producing the exploit, the impact is most likely limited to leading grub to crash causing a Denial-of-Service kind of attack or uncontrolled data corruption which presents a Low impact in the Integrity point of the CIA triad in the CVSS scoring.
Mitigation
As a mitigation Red Hat doesn't recommend to connect untrusted or unknown USB devices to the machine.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
The following CVSS metrics and score provided are preliminary and subject to review.
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 4.8 | N/A | 4.8 |
| Attack Vector | Physical | N/A | Physical |
| Attack Complexity | High | N/A | High |
| Privileges Required | None | N/A | None |
| User Interaction | None | N/A | None |
| Scope | Unchanged | N/A | Unchanged |
| Confidentiality | None | N/A | None |
| Integrity Impact | Low | N/A | Low |
| Availability Impact | High | N/A | High |
Vector
Red Hat: CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
cve.org: CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H
Understanding the Weakness (CWE)
Integrity,Availability,Confidentiality
Technical Impact: DoS: Crash, Exit, or Restart; Execute Unauthorized Code or Commands; Read Memory; Modify Memory
If the incorrect calculation is used in the context of memory allocation, then the software may create a buffer that is smaller or larger than expected. If the allocated buffer is smaller than expected, this could lead to an out-of-bounds read or write (CWE-119), possibly causing a crash, allowing arbitrary code execution, or exposing sensitive data.
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