# CVE-2026-125270: FFmpeg heap out-of-bounds read in v4l2_buffers

Source: https://junglewise.ai/threats/cve-2026-125270-ffmpeg-through-9-0-2-contains-a-heap-out-of-bounds-read  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-11-09. Updated: 2026-11-09  
License: CC BY 4.0 with a link back

CVE-2026-125270 · Severity: medium · CVSS 5.3 · Published 2026-11-09

FFmpeg is multimedia software used to encode and transcode audio and video files. When processing certain specially crafted video files (bottom-up AVI or PNM/PFM formats) through a V4L2 M2M encoder, a heap buffer read error can crash the application or leak sensitive memory contents into the encoded output.

Technologies: [Ffmpeg](https://junglewise.ai/threats/technologies/ffmpeg). Vendors: [Ffmpeg](https://junglewise.ai/threats/vendors/ffmpeg).

## Quick answers

**Is CVE-2026-125270 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125270 being exploited in the wild.

**How severe is CVE-2026-125270?** Medium severity, with a CVSS score of 5.3, published 9 November 2026.

**Which products and versions are affected?** Ffmpeg through 9.0.2.

**Is there a fix for CVE-2026-125270?** Yes: fixed in FFmpeg 9.0.3 (or later). Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-125270 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-125270?** Check whether you run Ffmpeg at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## How to fix

- Fixed in FFmpeg 9.0.3 (or later)

## Technical details

A heap out-of-bounds read vulnerability exists in the v4l2_buffer_swframe_to_buf() function in libavcodec/v4l2_buffers.c when handling frames with negative linesize. The bug occurs due to misalignment between V4L2 driver buffer dimensions and software frame dimensions during pixel copying. An attacker can supply maliciously crafted bottom-up video files that trigger the out-of-bounds read when transcoded using a V4L2 M2M encoder, causing denial of service or information disclosure.

## Affected products

- FFmpeg FFmpeg through 9.0.2

## Timeline

- 2026-11-09: disclosed
- 2026-11-03: patched

## References

- [https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24328](https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24328)
- [https://github.com/FFmpeg/FFmpeg](https://github.com/FFmpeg/FFmpeg)

## Related threats

- [FFmpeg double free in H.264 SEI message handling](https://junglewise.ai/threats/cve-2026-125269-ffmpeg-through-9-0-2-contains-a-double-free-vulnerability-in)
- [FFmpeg heap out-of-bounds write in APAC decoder](https://junglewise.ai/threats/cve-2026-125267-ffmpeg-before-8-1-3-and-9-x-before-9-0-2-contains-a-heap-out-of)
- [FFmpeg use-after-free in NVIDIA codec decoding](https://junglewise.ai/threats/cve-2026-125265-ffmpeg-through-9-0-2-contains-a-use-after-free-vulnerability-in)
- [FFmpeg JPEG XL parser uncontrolled resource consumption](https://junglewise.ai/threats/cve-2026-125264-ffmpeg-through-9-0-2-contains-an-uncontrolled-resource)
- [FFmpeg LCEVC dimension validation bypass memory exhaustion](https://junglewise.ai/threats/cve-2026-125263-ffmpeg-9-0-through-9-0-2-built-with-liblcevc-dec-fails-to)