# CVE-2022-28736: There's a use-after-free vulnerability in grub_cmd_chainloader() function

> An attacker with local access can trigger a use-after-free in GRUB2's chainloader command to achieve arbitrary code execution or expose sensitive data.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:L/AC:H/PR:H/UI:N/S:U/C:H/I:H/A:H`)
- **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:** 20 Jul 2023
- **Updated:** 13 Feb 2025
- **Also known as:** AZL-27554, AZL-34791, DEBIAN-CVE-2022-28736, GHSA-ff72-fwj3-6gh6, UBUNTU-CVE-2022-28736

## What is CVE-2022-28736?

CVE-2022-28736 is a medium-severity use after free vulnerability in GNU GRUB, published on 20 Jul 2023. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

There's a use-after-free vulnerability in grub_cmd_chainloader() function; The chainloader command is used to boot up operating systems that doesn't support multiboot and do not have direct support from GRUB2. When executing chainloader more than once a use-after-free vulnerability is triggered. If an attacker can control the GRUB2's memory allocation pattern sensitive data may be exposed and arbitrary code execution can be achieved.

Weakness: CWE-416 (Use After Free)

## Which versions are affected by CVE-2022-28736?

It affects 1 product.


Products: Gnu Grub2.

## How do I fix CVE-2022-28736?

Apply the vendor's patch.

## Is CVE-2022-28736 being exploited?

There is no known exploitation of CVE-2022-28736 in the wild and no public exploit code.

## Other vulnerabilities in GNU GRUB

- [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-2022-28736 and fix it if it is affected.

What it is: CVE-2022-28736 is a medium-severity use after free vulnerability in GNU GRUB, published on 20 Jul 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-2022-28736 in the wild and no public exploit code.

Affected product: GNU GRUB. 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-2022-28736/ (Markdown: https://insights.sbomify.com/CVE-2022-28736/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2022-28736
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2022-28736
- OSV: https://osv.dev/vulnerability/CVE-2022-28736

---
From sbomify Insights: https://insights.sbomify.com/CVE-2022-28736/
Summaries are generated and may contain mistakes; the official description above is the record.