---
id: "CVE-2026-125253"
page: "https://infrastack.ai/live/CVE-2026-125253"
kind: "vulnerability"
aliases: ["CVE-2026-125253"]
title: "FFmpeg: crafted VP9 packet overflows size check, crashing 32-bit builds"
severity: "medium"
cvss: 5.8
epss: null
exploited: false
status: "open"
category: "runtime"
products: [{"name": "FFmpeg", "fixed": [], "affected": "", "ecosystem": "vendor"}]
ecosystems: ["vendor"]
tags: ["32-bit", "ffmpeg", "libavcodec", "runtime", "vp9"]
not_affected_if: ["64-bit-build", "trusted-input-only"]
published_at: "2026-11-09T20:18:11+00:00"
first_seen_at: "2026-11-09T20:48:13+00:00"
updated_at: "2026-11-09T20:49:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125253", "first_seen_at": "2026-11-09T20:48:13+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted VP9 packet overflows size check, crashing 32-bit builds

Link for people: https://infrastack.ai/live/CVE-2026-125253 (this .md is for agents)

FFmpeg's VP9 superframe parser miscalculates frame sizes on 32-bit builds due to an integer overflow in cbs_vp9_split_fragment(). A crafted VP9 packet with a forged superframe index causes out-of-bounds reads that crash the application.

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

## Affected

- vendor:FFmpeg affected range not listed fixed no fixed version listed

## How to check

- Check the FFmpeg version with `ffmpeg -version`, and compare it against the fixed version.
- Confirm whether you run a 32-bit FFmpeg build (unknown whether the sources give a command for this).

## Timeline

- 2026-11-09T20:48:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125253

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-vp9-cbs-superframe-integer-overflow-out-of-bounds-read
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/6280907da48c4dd78f95ef5c713a29c7702153a3

## From the sources

FFmpeg through 9.0.2 contains an integer overflow in cbs_vp9_split_fragment() in libavcodec/cbs_vp9.c that wraps the superframe size check on 32-bit builds. Attackers can supply a crafted VP9 packet with a forged superframe index containing near-2^32 frame sizes, causing out-of-bounds reads that crash 32-bit applications.

---

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