# CVE-2026-125254: FFmpeg division by zero in VVC decoder

Source: https://junglewise.ai/threats/cve-2026-125254-ffmpeg-through-9-0-2-contains-a-division-by-zero-vulnerability  
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-2026-125254 · Severity: medium · CVSS 5.5 · Published 2026-11-09

FFmpeg is a multimedia framework used to decode and process video and audio files. A crafted video file in the VVC format can cause FFmpeg's decoder to crash due to improper validation of reference indices, potentially disrupting video playback or streaming services that rely on FFmpeg.

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

## Quick answers

**Is CVE-2026-125254 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125254 being exploited in the wild.

**How severe is CVE-2026-125254?** Medium severity, with a CVSS score of 5.5, published 9 November 2026.

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

**Is there a fix for CVE-2026-125254?** Yes: fixed in FFmpeg 9.1. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-125254 attacked?** It is attacked over the network or with local access, in a software library.

**Am I affected by CVE-2026-125254?** 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 9.1

## Technical details

The VVC decoder in FFmpeg fails to validate that the number of active reference indices does not exceed the number of reference list entries in ff_vvc_slice_rpl(), resulting in a division by zero in ff_vvc_mv_scale() when processing a crafted bitstream. An attacker can supply a malicious VVC video file that triggers this crash via network delivery or as a local file. The vulnerability is fixed by rejecting slices where num_ref_entries is less than NumRefIdxActive as required by the H.266 specification.

## Affected products

- FFmpeg FFmpeg through 9.0.2

## Timeline

- 2026-11-09: disclosed
- 2026-11-03: patched: Fix merged in PR #25572

## References

- [https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25572](https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25572)
- [https://github.com/FFmpeg/FFmpeg](https://github.com/FFmpeg/FFmpeg)

## Related threats

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- [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)
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- [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)