# CVE-2026-125262: FFmpeg heap buffer overflow in LCEVC decoder

Source: https://junglewise.ai/threats/cve-2026-125262-ffmpeg-through-9-0-2-contains-a-heap-buffer-overflow  
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-2026-125262 · Severity: high · CVSS 7.8 · Published 2026-11-09

FFmpeg is a widely-used multimedia library that decodes video streams including H.264 and HEVC formats. An attacker can craft malicious video files with inconsistent dimension data that causes the decoder to write beyond allocated memory, potentially allowing code execution or application crashes on systems that process untrusted video content.

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

## Quick answers

**Is CVE-2026-125262 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125262 being exploited in the wild.

**How severe is CVE-2026-125262?** High severity, with a CVSS score of 7.8, published 9 November 2026.

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

**Is there a fix for CVE-2026-125262?** 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-2026-125262 attacked?** It is attacked over the network, in a software library.

**Am I affected by CVE-2026-125262?** 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

A heap buffer overflow exists in libavcodec/lcevcdec.c where LCEVC enhancement layer output picture dimensions are not validated against the allocated frame buffer. Attackers embed crafted LCEVC enhancement data with mismatched global configurations in H.264 or HEVC streams to trigger out-of-bounds writes. The vulnerability requires network access to deliver the malicious stream but no user interaction beyond normal video playback.

## Affected products

- FFmpeg FFmpeg through 9.0.2

## Timeline

- 2026-11-09: disclosed
- 2026-10-28: patched: PR #25067 merged

## References

- [https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25067](https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25067)
- [https://github.com/FFmpeg/FFmpeg](https://github.com/FFmpeg/FFmpeg)

## Related threats

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- [FFmpeg JPEG XL parser uncontrolled resource consumption](https://junglewise.ai/threats/cve-2026-125264-ffmpeg-through-9-0-2-contains-an-uncontrolled-resource)