---
id: "CVE-2026-125181"
page: "https://infrastack.ai/live/CVE-2026-125181"
kind: "vulnerability"
aliases: ["CVE-2026-125181"]
title: "FFmpeg: crafted FLIC file corrupts heap memory on big-endian builds"
severity: "high"
cvss: 7.3
epss: null
exploited: false
status: "open"
category: "package"
products: [{"name": "ffmpeg", "fixed": [], "affected": "<= 9.0.2 (big-endian builds only)", "ecosystem": "vendor"}]
ecosystems: []
tags: ["big-endian", "ffmpeg", "libavcodec", "media-processing", "package", "powerpc", "s390x"]
not_affected_if: ["arm64", "little-endian", "little-endian-build", "no-flic-decoding", "trusted-input-only", "x86"]
published_at: "2026-11-09T19:16:53+00:00"
first_seen_at: "2026-11-09T19:28:17+00:00"
updated_at: "2026-11-09T19:34:56+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-125181", "first_seen_at": "2026-11-09T19:28:17+00:00"}, {"source": "analyst", "url": null, "first_seen_at": "2026-11-09T19:34:56+00:00"}]
exploit_sources: []
---

# FFmpeg: crafted FLIC file corrupts heap memory on big-endian builds

Link for people: https://infrastack.ai/live/CVE-2026-125181 (this .md is for agents)

FFmpeg's FLIC video decoder writes past the end of a frame buffer when it reads a crafted 15/16 bpp FLI_BRUN chunk on big-endian builds. An attacker who supplies such a file can corrupt heap memory and crash the process.

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

## Affected

- vendor:ffmpeg affected <= 9.0.2 (big-endian builds only) fixed no fixed version listed

## How to check

Little-endian hosts (x86-64, typical arm64) are not affected. On big-endian hosts (s390x, some PowerPC/MIPS), run 'ffmpeg -version'; versions up to 9.0.2 are affected unless built from source containing commit c0d308a9a616f4abcc4e0a4d86f7de92ecdef9f6 (also check distro backports). Check whether pipelines decode untrusted FLIC/FLX (15/16 bpp) files with ffmpeg/libavcodec.

## Timeline

- 2026-11-09T19:28:17+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-125181
- 2026-11-09T19:34:56+00:00 analyst — Read vulncheck advisory and commit c0d308a (via WebFetch; web-cli Exa out of credits). Affected FFmpeg <= 9.0.2, big-endian only (reproduced on s390x/qemu); fix is a one-line change in flicvideo.c FLI_BRUN swap (reads decoded pixels, not packet). No fixed release named in sources; fix left unknown, nothing marked verified. Commit message says out-of-array read, advisory says OOB write. No exploitation or PoC seen. Did not search X/HN.

## Documents

- [advisory] Third-party advisory: www.vulncheck.com https://www.vulncheck.com/advisories/ffmpeg-through-9.0.2-flic-decoder-out-of-bounds-write-via-fli-brun-byte-swap
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/c0d308a9a616f4abcc4e0a4d86f7de92ecdef9f6
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/eb47d7bb6cf13042c6ab14e22fc0c0c3a6e51e12
- [fix] Patch: github.com https://github.com/FFmpeg/FFmpeg/commit/ee30fb98c0d4e97abbd5e371d2a3a926e92bec70

## From the sources

FFmpeg through 9.0.2 contains an out-of-bounds write vulnerability in flic_decode_frame_15_16BPP() in libavcodec/flicvideo.c that allows attackers to corrupt heap memory on big-endian builds. Attackers can supply a crafted 15/16 bpp FLIC/FLX file with an FLI_BRUN chunk whose non-terminating byte-swap loop writes packet-derived data past the frame buffer, crashing the process.

---

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