# CVE-2026-125267: FFmpeg heap out-of-bounds write in APAC decoder

Source: https://junglewise.ai/threats/cve-2026-125267-ffmpeg-before-8-1-3-and-9-x-before-9-0-2-contains-a-heap-out-of  
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-2026-125267 · Severity: high · CVSS 7.8 · Published 2026-11-09

FFmpeg is a multimedia processing framework used to encode, decode, and transcode audio and video. A flaw in the APAC audio decoder allows an attacker to supply a malicious audio file that causes heap memory corruption or crashes the application during playback or transcoding operations.

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

## Quick answers

**Is CVE-2026-125267 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-125267 being exploited in the wild.

**How severe is CVE-2026-125267?** High severity, with a CVSS score of 7.8, published 9 November 2026.

**Which products and versions are affected?** Ffmpeg before 8.1.3 and 9.x before 9.0.2.

**Is there a fix for CVE-2026-125267?** Yes: fixed in FFmpeg 8.1.3, 9.0.2. Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.

**How is CVE-2026-125267 attacked?** It is attacked with local access, in a software library.

**Am I affected by CVE-2026-125267?** 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 8.1.3, 9.0.2

## Technical details

The APAC decoder in libavcodec/apac.c fails to reset the bitstream_index variable, allowing it to accumulate unchecked across packets. A crafted APAC file can trigger an integer overflow in the bitstream_index when adding the next buffer size, bypassing the reallocation bounds check and causing memcpy() to write beyond allocated heap memory or crash the process.

## Affected products

- FFmpeg FFmpeg before 8.1.3 and 9.x before 9.0.2

## Timeline

- 2026-11-09: disclosed
- 2026-09-12: patched

## References

- [https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24432](https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24432)
- [https://github.com/FFmpeg/FFmpeg](https://github.com/FFmpeg/FFmpeg)

## Related threats

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- [FFmpeg double free in H.264 SEI message handling](https://junglewise.ai/threats/cve-2026-125269-ffmpeg-through-9-0-2-contains-a-double-free-vulnerability-in)
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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)
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