---
id: "CVE-2026-125251"
page: "https://infrastack.ai/live/CVE-2026-125251"
kind: "vulnerability"
aliases: ["CVE-2026-125251"]
title: "FFmpeg: VVC decoder integer overflow lets crafted video corrupt memory"
severity: "high"
cvss: 7.3
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "ffmpeg", "fixed": [], "affected": "<= 9.0.2 (32-bit builds with the VVC decoder)", "ecosystem": "vendor"}]
ecosystems: []
tags: ["ffmpeg", "libavcodec", "media-processing", "package", "self-hosted"]
not_affected_if: ["64-bit-build", "no-vvc-input"]
published_at: "2026-11-09T19:17:04+00:00"
first_seen_at: "2026-11-09T19:28:21+00:00"
updated_at: "2026-11-09T19:30:30+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125251", "first_seen_at": "2026-11-09T19:28:21+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-11-09T19:30:30+00:00"}]
exploit_sources: []
---

# FFmpeg: VVC decoder integer overflow lets crafted video corrupt memory

Link for people: https://infrastack.ai/live/CVE-2026-125251 (this .md is for agents)

FFmpeg's VVC (H.266) decoder multiplies the number of NAL units by a struct size without an overflow check in alloc_frame(). On 32-bit builds this undersizes the reference picture list buffer, so a crafted file with very many NAL units causes heap out-of-bounds writes. The maintainer fix was replicated under ASAN on an i386 build.

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

## Affected

- vendor:ffmpeg affected <= 9.0.2 (32-bit builds with the VVC decoder) fixed no fixed version listed

## How to check

- Run ffmpeg -version: releases up to and including 9.0.2 are listed as affected, unless your distro backported commit 053660fd.
- Check for a 32-bit build (i386/armhf; file $(which ffmpeg), or ffmpeg -version configuration line). The overflow was shown on i386; 64-bit is not stated to be affected.
- Check the VVC decoder is built in: ffmpeg -decoders | grep -i vvc.
- Also check libavcodec used as a library by other apps (media pipelines, thumbnailers) that decode untrusted video.

## Fix

Fixed upstream in FFmpeg commit 053660fdb0d2403b838690689c47ad7685c3b10b (avcodec/vvc/refs: check the rpl allocation size for overflow). No release containing it is named in the sources; until one is confirmed, build from a source tree that includes the commit or apply the patch. Releases through 9.0.2 are listed as affected.

## Timeline

- 2026-11-09T19:28:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125251
- 2026-11-09T19:30:30+00:00 analyst — Exa unavailable (no credits); read commit and VulnCheck via WebFetch. Commit by Niedermayer, found by Joshua Rogers (AISLE), repro on i386. VulnCheck names no fixed release, no exploitation or PoC. 64-bit not-affected is implied, not stated. Fix field not marked verified: commit page was read via fetch summary, no release.

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-vvc-decoder-heap-out-of-bounds-write-via-refs-c
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/053660fdb0d2403b838690689c47ad7685c3b10b

## From the sources

FFmpeg through 9.0.2 contains an integer overflow vulnerability in the VVC decoder alloc_frame() function in libavcodec/vvc/refs.c that undersizes the reference picture list allocation on 32-bit builds. Attackers can supply a crafted VVC (H.266) file with a very large number of NAL units per access unit to trigger heap out-of-bounds writes and corrupt memory.

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