---
id: "CVE-2026-125199"
page: "https://infrastack.ai/live/CVE-2026-125199"
kind: "vulnerability"
aliases: ["CVE-2026-125199"]
title: "FFmpeg: crafted VC-1 video files exhaust memory in decoding applications"
severity: "medium"
cvss: 6.8
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["ffmpeg", "libavcodec", "media-processing", "package"]
not_affected_if: ["no-untrusted-media", "vc1-not-decoded"]
published_at: "2026-11-09T19:16:56+00:00"
first_seen_at: "2026-11-09T19:28:18+00:00"
updated_at: "2026-11-09T19:31:30+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125199", "first_seen_at": "2026-11-09T19:28:18+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted VC-1 video files exhaust memory in decoding applications

Link for people: https://infrastack.ai/live/CVE-2026-125199 (this .md is for agents)

FFmpeg's VC-1 decoder in libavcodec leaks slice buffers when a bit reader initialization fails. An attacker who supplies a crafted VC-1 file with repeated oversized slices can exhaust the memory of any application decoding it.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check the installed FFmpeg version with `ffmpeg -version`, comparing against the product range in the sources (through 9.0.2).
- Find applications that decode untrusted VC-1 media through libavcodec, such as media servers or transcoders.

## Timeline

- 2026-11-09T19:28:18+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125199

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-memory-leak-in-vc-1-decoder-via-vc1-decode-frame
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/afdc555aace698b88c86d3f33a7773a6c8ba2897

## From the sources

FFmpeg through 9.0.2 contains a memory leak vulnerability in vc1_decode_frame() in libavcodec/vc1dec.c that leaks slice buffers when init_get_bits8() fails. Attackers can supply crafted files with repeated oversized VC-1 slices exceeding the bit reader limit to exhaust memory of decoding applications.

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_Free to read, with fair use of about 60 pages a minute. For higher limits or API access: sales@infrastack.ai_