# CVE-2024-56738: Information disclosure in GRUB2

> Attackers can exploit timing side-channels in GRUB's cryptographic comparison to potentially recover sensitive data.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 29 Dec 2024
- **Updated:** 31 Dec 2024
- **Also known as:** AZL-54692, AZL-54709, BELL-CVE-2024-56738, CLSA-2026-1788432569, DEBIAN-CVE-2024-56738, GHSA-9gmj-v2m8-qffv, OESA-2025-1675, SUSE-SU-2025:02705-1, SUSE-SU-2025:02706-1, SUSE-SU-2025:02724-1, SUSE-SU-2025:02725-1, SUSE-SU-2025:02727-1, SUSE-SU-2025:02772-1, SUSE-SU-2025:02813-1, SUSE-SU-2025:20654-1, UBUNTU-CVE-2024-56738, openSUSE-SU-2025:15400-1

## What is CVE-2024-56738?

CVE-2024-56738 is a medium-severity vulnerability in GNU GRUB2, published on 29 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

GNU GRUB (aka GRUB2) through 2.12 does not use a constant-time algorithm for grub_crypto_memcmp and thus allows side-channel attacks.

Weakness: CWE-203 (Observable Discrepancy), CWE-208 (Observable Timing Discrepancy)

## Which versions are affected by CVE-2024-56738?

It affects 1 product.


| Package | Ecosystem | Affected | Fixed in |
| --- | --- | --- | --- |
| `grub2` | SUSE:Linux Enterprise Micro 5.1 | All versions | 2.04-150300.3.14.2 |
| `grub2` | SUSE:Linux Enterprise Micro 5.2 | All versions | 2.04-150300.22.58.1 |
| `grub2` | SUSE:Linux Enterprise Micro 5.3 | All versions | 2.06-150400.11.63.1 |
| `grub2` | SUSE:Linux Enterprise Micro 5.4 | All versions | 2.06-150400.11.63.1 |
| `grub2` | SUSE:Linux Enterprise Micro 5.5 | All versions | 2.06-150500.29.53.1 |
| `grub2` | SUSE:Linux Enterprise Module for Basesystem 15 SP6 | All versions | 2.12-150600.8.34.1 |
| `grub2` | SUSE:Linux Enterprise Module for Basesystem 15 SP7 | All versions | 2.12-150700.19.13.2 |
| `grub2` | SUSE:Linux Enterprise Module for Server Applications 15 SP6 | All versions | 2.12-150600.8.34.1 |
| `grub2` | SUSE:Linux Enterprise Module for Server Applications 15 SP7 | All versions | 2.12-150700.19.13.2 |
| `grub2` | SUSE:Linux Enterprise Server LTSS Extended Security 12 SP5 | All versions | 2.02-190.1 |
| `grub2` | SUSE:Linux Micro 6.0 | All versions | 2.12~rc1-7.1 |
| `grub2` | openSUSE:Leap 15.6 | All versions | 2.12-150600.8.34.1 |
| `grub2` | openSUSE:Tumbleweed | All versions | 2.12-56.1 |

Products: Gnu Grub2.

## How do I fix CVE-2024-56738?

Apply the vendor's patch.

## Is CVE-2024-56738 being exploited?

There is no known exploitation of CVE-2024-56738 in the wild and no public exploit code.

## Other vulnerabilities in GNU GRUB2

- [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-2024-56738 and fix it if it is affected.

What it is: CVE-2024-56738 is a medium-severity vulnerability in GNU GRUB2, published on 29 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-56738 in the wild and no public exploit code.

Affected product: GNU GRUB2. 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-2024-56738/ (Markdown: https://insights.sbomify.com/CVE-2024-56738/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56738
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56738
- OSV: https://osv.dev/vulnerability/CVE-2024-56738

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56738/
Summaries are generated and may contain mistakes; the official description above is the record.