---
id: "CVE-2026-125249"
page: "https://infrastack.ai/live/CVE-2026-125249"
kind: "vulnerability"
aliases: ["CVE-2026-125249"]
title: "FFmpeg: integer overflow in Vulkan decoder lets crafted video write memory"
severity: "high"
cvss: 7.3
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "ffmpeg", "fixed": [], "affected": ">= 7.1, <= 9.0.2", "ecosystem": "vendor"}]
ecosystems: []
tags: ["ffmpeg", "libavcodec", "media-processing", "package", "self-hosted", "vulkan"]
not_affected_if: ["default-config", "trusted-input-only"]
published_at: "2026-11-09T19:17:03+00:00"
first_seen_at: "2026-11-09T19:28:21+00:00"
updated_at: "2026-11-09T19:31:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125249", "first_seen_at": "2026-11-09T19:28:21+00:00"}, {"source": "analyst", "url": "https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25136", "first_seen_at": "2026-11-09T19:31:47+00:00", "cites": ["https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25136"]}]
exploit_sources: []
---

# FFmpeg: integer overflow in Vulkan decoder lets crafted video write memory

Link for people: https://infrastack.ai/live/CVE-2026-125249 (this .md is for agents)

FFmpeg 7.1 through 9.0.2 miscalculates the Vulkan hardware-decode buffer size when a stream carries over 2 GiB of slice data per frame. The resulting memcpy writes past a smaller pooled buffer, which can corrupt memory when FFmpeg decodes a crafted file.

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

## Affected

- vendor:ffmpeg affected >= 7.1, <= 9.0.2 fixed no fixed version listed

## How to check

- Run `ffmpeg -version`; versions 7.1 through 9.0.2 are in the affected range.
- Run `ffmpeg -hwaccels`; only builds listing `vulkan` have the vulnerable path, and only when decoding is actually run with `-hwaccel vulkan` (or an app that selects Vulkan decode).
- Also check any app or library that bundles libavcodec (media pipelines, thumbnailers) for the same versions.

## Fix

No released fix as of 2026-11-09. Upstream PR #25136 (commit 09a6683754 'Vulkan decode: limits a frame's slice data to 2 GiB') is open, not merged, targeted at the 9.1 milestone. Until a release ships, avoid Vulkan hwaccel decoding of untrusted files (use software decode).

## Timeline

- 2026-11-09T19:28:21+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125249
- 2026-11-09T19:31:47+00:00 analyst https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25136 — Read vulncheck advisory (no fixed version, no exploit/PoC stated) and upstream PR 25136, which is open/unmerged with commit 09a6683754 limiting slice data to 2 GiB; fix_status none based on PR state, not a vendor statement, so nothing marked verified. X/web search not attempted (credits exhausted per notes).

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-7.1-through-9.0.2-heap-out-of-bounds-write-via-vulkan-slice-buffer-sizing
- [describes] FFmpeg PR 25136: libavcodec fixes (HEVC/AV1 hwaccel tile arrays, Vulkan) - open https://code.ffmpeg.org/FFmpeg/FFmpeg/pulls/25136

## From the sources

FFmpeg 7.1 through 9.0.2 contains an integer overflow in ff_vk_decode_add_slice() in libavcodec/vulkan_decode.c that miscalculates the Vulkan hwaccel bitstream buffer size. Attackers can supply a crafted stream with over 2 GiB of slice data per frame, causing memcpy() to write past a smaller pooled host-mapped buffer.

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