# CVE-2023-4693: Grub2: out-of-bounds read at fs/ntfs.c

> A physically present attacker can leak sensitive memory or EFI variables via a crafted NTFS image in the GRUB2 bootloader.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:C/C:H/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 25 Oct 2023
- **Updated:** 21 Jul 2026
- **Also known as:** AZL-31685, AZL-34794, BELL-CVE-2023-4693, CLSA-2024-1724433427, CLSA-2024-1724434789, CLSA-2024-1724871398, DEBIAN-CVE-2023-4693, GHSA-r62p-gp92-7444, UBUNTU-CVE-2023-4693

## What is CVE-2023-4693?

CVE-2023-4693 is a medium-severity vulnerability in Redhat Enterprise Linux, published on 25 Oct 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An out-of-bounds read flaw was found on grub2's NTFS filesystem driver. This issue may allow a physically present attacker to present a specially crafted NTFS file system image to read arbitrary memory locations. A successful attack allows sensitive data cached in memory or EFI variable values to be leaked, presenting a high Confidentiality risk.

Weakness: CWE-125 (Out-of-bounds Read)

## Which versions are affected by CVE-2023-4693?

It affects 2 products.


Products: Gnu Grub2, Redhat Enterprise Linux.

## How do I fix CVE-2023-4693?

Apply the vendor's patch.

## Is CVE-2023-4693 being exploited?

There is no known exploitation of CVE-2023-4693 in the wild and no public exploit code.

## Other vulnerabilities in Redhat Enterprise Linux

- [CVE-2024-56737](https://insights.sbomify.com/CVE-2024-56737/): Memory corruption in GRUB2 (high 8.8)
- [CVE-2022-28733](https://insights.sbomify.com/CVE-2022-28733/): Integer underflow in grub_net_recv_ip4_packets (high 8.1)
- [CVE-2022-28734](https://insights.sbomify.com/CVE-2022-28734/): Out-of-bounds write when handling split HTTP headers (high 8.1)
- [CVE-2025-61662](https://insights.sbomify.com/CVE-2025-61662/): Grub2: missing unregister call for gettext command may lead to use-after-free (high 7.8)
- [CVE-2024-45782](https://insights.sbomify.com/CVE-2024-45782/): Grub2: fs/hfs: strcpy() using the volume name (fs/hfs.c:382) (high 7.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-4693 and fix it if it is affected.

What it is: CVE-2023-4693 is a medium-severity vulnerability in Redhat Enterprise Linux, published on 25 Oct 2023. 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-2023-4693 in the wild and no public exploit code.

Affected product: Redhat Enterprise Linux. 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-2023-4693/ (Markdown: https://insights.sbomify.com/CVE-2023-4693/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-4693
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-4693
- OSV: https://osv.dev/vulnerability/CVE-2023-4693

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-4693/
Summaries are generated and may contain mistakes; the official description above is the record.