# CVE-2021-40944: Null dereference in n/a

> A null pointer dereference in GPAC MP4Box allows attackers to cause a denial of service via crafted input.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 28 Jun 2022
- **Updated:** 4 Aug 2024
- **Also known as:** DEBIAN-CVE-2021-40944, GHSA-3fqc-qhh2-fxhg, UBUNTU-CVE-2021-40944

## What is CVE-2021-40944?

CVE-2021-40944 is a medium-severity vulnerability in Gpac Gpac, published on 28 Jun 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

In GPAC MP4Box 1.1.0, there is a Null pointer reference in the function gf_filter_pid_get_packet function in src/filter_core/filter_pid.c:5394, as demonstrated by GPAC. This can cause a denial of service (DOS).

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2021-40944?

It affects 1 product.


Products: Gpac Gpac.

## How do I fix CVE-2021-40944?

Upgrade to a fixed version.

## Is CVE-2021-40944 being exploited?

There is no known exploitation of CVE-2021-40944 in the wild and no public exploit code.

## Other vulnerabilities in Gpac Gpac

- [CVE-2023-46427](https://insights.sbomify.com/CVE-2023-46427/): Null dereference in n/a (critical 9.8)
- [CVE-2023-46932](https://insights.sbomify.com/CVE-2023-46932/): Memory corruption in n/a (critical 9.8)
- [CVE-2022-36190](https://insights.sbomify.com/CVE-2022-36190/): Use after free in n/a (critical 9.8)
- [CVE-2021-28300](https://insights.sbomify.com/CVE-2021-28300/): Null dereference in n/a (critical 9.8)
- [CVE-2020-11558](https://insights.sbomify.com/CVE-2020-11558/): Use after free in n/a (critical 9.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-40944 and fix it if it is affected.

What it is: CVE-2021-40944 is a medium-severity vulnerability in Gpac Gpac, published on 28 Jun 2022. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2021-40944 in the wild and no public exploit code.

Affected product: Gpac Gpac. 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-2021-40944/ (Markdown: https://insights.sbomify.com/CVE-2021-40944/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-40944
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-40944
- OSV: https://osv.dev/vulnerability/CVE-2021-40944

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-40944/
Summaries are generated and may contain mistakes; the official description above is the record.