# CVE-2025-61661: Grub2: grub2: out-of-bounds write via malicious usb device

> A local attacker can cause a denial of service or data corruption in GRUB by connecting a malicious USB device during boot.

- **Severity:** Medium 4.8 (`CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:N/I:L/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 18 Nov 2025
- **Updated:** 1 Sep 2026
- **Also known as:** AZL-70526, AZL-70580, DEBIAN-CVE-2025-61661, GHSA-cjch-253g-8hp2, UBUNTU-CVE-2025-61661

## What is CVE-2025-61661?

CVE-2025-61661 is a medium-severity memory corruption vulnerability in GNU Red Hat Enterprise Linux 10, published on 18 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.

### Official 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.

Weakness: CWE-131 (Incorrect Calculation of Buffer Size)

## Which versions are affected by CVE-2025-61661?


## How do I fix CVE-2025-61661?

Apply the vendor's patch.

## Is CVE-2025-61661 being exploited?

There is no known exploitation of CVE-2025-61661 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-61661 and fix it if it is affected.

What it is: CVE-2025-61661 is a medium-severity memory corruption vulnerability in GNU Red Hat Enterprise Linux 10, published on 18 Nov 2025. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2025-61661 in the wild and no public exploit code.

Affected product: GNU Red Hat Enterprise Linux 10. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2025-61661/ (Markdown: https://insights.sbomify.com/CVE-2025-61661/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-61661
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-61661
- OSV: https://osv.dev/vulnerability/CVE-2025-61661

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-61661/
Summaries are generated and may contain mistakes; the official description above is the record.