# CVE-2025-9951: Remote code execution via Heap Buffer Overflow in FFmpeg JPEG2000

> Attackers can achieve remote code execution or cause denial of service via a heap buffer overflow in FFmpeg's JPEG2000 decoder.

- **Severity:** High 7.2 (`CVSS:4.0/AV:N/AC:H/AT:N/PR:L/UI:N/VC:N/VI:H/VA:H/SC:N/SI:H/SA:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 9 Sep 2025
- **Updated:** 26 Feb 2026
- **Also known as:** DEBIAN-CVE-2025-9951, GHSA-39q3-f8jq-v6mg, JLSEC-2026-648, UBUNTU-CVE-2025-9951

## What is CVE-2025-9951?

CVE-2025-9951 is a high-severity memory corruption vulnerability in FFmpeg, published on 9 Sep 2025. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A heap-buffer-overflow write exists in jpeg2000dec FFmpeg which allows an attacker to potentially gain remote code execution or cause denial of service via the channel definition cdef atom of JPEG2000.

Weakness: CWE-122 (Heap-based Buffer Overflow)

## Which versions are affected by CVE-2025-9951?


## How do I fix CVE-2025-9951?

Upgrade to a fixed version.

## Is CVE-2025-9951 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-9951 exists.

Public exploit code:

- https://github.com/fm0ss/cve-2025-9951-ffmpeg-jp2-poc (github_poc): https://github.com/fm0ss/cve-2025-9951-ffmpeg-jp2-poc

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-9951 and fix it if it is affected.

What it is: CVE-2025-9951 is a high-severity memory corruption vulnerability in FFmpeg, published on 9 Sep 2025. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2025-9951 exists.

Affected product: FFmpeg. 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-2025-9951/ (Markdown: https://insights.sbomify.com/CVE-2025-9951/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-9951
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-9951
- OSV: https://osv.dev/vulnerability/CVE-2025-9951

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-9951/
Summaries are generated and may contain mistakes; the official description above is the record.