# CVE-2021-3696: Memory corruption in grub2

> Heap out-of-bounds write in GRUB2 PNG reader allows potential arbitrary code execution or secure boot circumvention via crafted images.

- **Severity:** Medium 4.5 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:L/I:L/A:L`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 6 Jul 2022
- **Updated:** 3 Aug 2024
- **Also known as:** AZL-31035, AZL-34784, DEBIAN-CVE-2021-3696, GHSA-mv5h-82v3-mq2x, UBUNTU-CVE-2021-3696

## What is CVE-2021-3696?

CVE-2021-3696 is a medium-severity memory corruption vulnerability in Netapp Ontap Select Deploy Administration Utility, published on 6 Jul 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

A heap out-of-bounds write may heppen during the handling of Huffman tables in the PNG reader. This may lead to data corruption in the heap space. Confidentiality, Integrity and Availablity impact may be considered Low as it's very complex to an attacker control the encoding and positioning of corrupted Huffman entries to achieve results such as arbitrary code execution and/or secure boot circumvention. This flaw affects grub2 versions prior grub-2.12.

Weakness: CWE-787 (Out-of-bounds Write)

## Which versions are affected by CVE-2021-3696?

It affects 13 products.


Products: Gnu Grub2, Netapp Ontap Select Deploy Administration Utility, Redhat Codeready Linux Builder, Redhat Developer Tools, Redhat Enterprise Linux, Redhat Enterprise Linux Eus, Redhat Enterprise Linux for Power Little Endian, Redhat Enterprise Linux for Power Little Endian Eus, Redhat Enterprise Linux Server Aus, Redhat Enterprise Linux Server for Power Little Endian Update Services for Sap Solutions, Redhat Enterprise Linux Server Tus, Redhat Openshift, Redhat Openshift Container Platform.

## How do I fix CVE-2021-3696?

Upgrade to a fixed version.

## Is CVE-2021-3696 being exploited?

There is no known exploitation of CVE-2021-3696 in the wild and no public exploit code.

## Other vulnerabilities in Netapp Ontap Select Deploy Administration Utility

- [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-2021-3696 and fix it if it is affected.

What it is: CVE-2021-3696 is a medium-severity memory corruption vulnerability in Netapp Ontap Select Deploy Administration Utility, published on 6 Jul 2022. 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-2021-3696 in the wild and no public exploit code.

Affected product: Netapp Ontap Select Deploy Administration Utility. 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-2021-3696/ (Markdown: https://insights.sbomify.com/CVE-2021-3696/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-3696
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-3696
- OSV: https://osv.dev/vulnerability/CVE-2021-3696

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-3696/
Summaries are generated and may contain mistakes; the official description above is the record.