# CVE-2026-33144: GPAC MP4Box Heap Buffer Overflow Write in gf_xml_parse_bit_sequence_bs (NHML BS Parsing)

> A heap buffer overflow in GPAC MP4Box allows attackers to execute arbitrary code or cause denial of service via crafted NHML files.

- **Severity:** Medium 5.8 (`CVSS:3.1/AV:L/AC:H/PR:N/UI:R/S:U/C:L/I:L/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:** No
- **Published:** 20 Mar 2026
- **Updated:** 20 Mar 2026
- **Also known as:** DEBIAN-CVE-2026-33144, GHSA-3jw5-9pmw-vmfg, UBUNTU-CVE-2026-33144

## What is CVE-2026-33144?

CVE-2026-33144 is a medium-severity memory corruption vulnerability in Gpac Gpac, published on 20 Mar 2026. 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

GPAC is an open-source multimedia framework. Prior to commit 86b0e36, a heap-based buffer overflow (write) vulnerability was discovered in GPAC MP4Box. The vulnerability exists in the gf_xml_parse_bit_sequence_bs function in utils/xml_bin_custom.c when processing a crafted NHML file containing malicious <BS> (BitSequence) elements. An attacker can exploit this by providing a specially crafted NHML file, causing an out-of-bounds write on the heap. This issue has been via commit 86b0e36.

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

## Which versions are affected by CVE-2026-33144?

It affects 1 product.


Products: Gpac Gpac.

## How do I fix CVE-2026-33144?

No fix has been published for CVE-2026-33144 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-33144 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33144 exists.

## 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-2026-33144 and fix it if it is affected.

What it is: CVE-2026-33144 is a medium-severity memory corruption vulnerability in Gpac Gpac, published on 20 Mar 2026. 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: It is not confirmed as exploited in the wild, but public exploit code for CVE-2026-33144 exists.

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-2026-33144/ (Markdown: https://insights.sbomify.com/CVE-2026-33144/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-33144
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-33144
- OSV: https://osv.dev/vulnerability/CVE-2026-33144

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-33144/
Summaries are generated and may contain mistakes; the official description above is the record.