---
id: "CVE-2026-111728"
kind: "vulnerability"
aliases: ["CVE-2026-111728"]
title: "Seanime: unauthenticated ffmpeg flag injection enables file writes and reads"
severity: "medium"
cvss: 5.4
epss: null
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["media-server", "package", "seanime", "self-hosted", "tailscale"]
not_affected_if: ["localhost-only", "version-outside-range"]
published_at: "2026-10-16T15:17:15+00:00"
first_seen_at: "2026-10-23T21:57:13+00:00"
updated_at: "2026-10-25T04:18:32+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-111728", "first_seen_at": "2026-10-23T21:57:13+00:00"}]
---

# Seanime: unauthenticated ffmpeg flag injection enables file writes and reads

Seanime versions 3.7.0 through 3.10.3 let unauthenticated clients on the local network or Tailnet set custom ffmpeg decode and encode flags that are passed verbatim to ffmpeg. An attacker can use this to write or truncate arbitrary files as the user running Seanime, and possibly read local files or send data outbound through ffmpeg protocol handlers.

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

## How to check

- Check the installed Seanime version and see whether it falls between `3.7.0` and `3.10.3`
- Check whether the mediastream transcoding setting `transcodeHwAccel` is set to `custom` in the Seanime configuration
- unknown whether other checks are needed

## Fix

- Upgrade Seanime to a version later than `3.10.3` (the fixed version is not stated in the sources)
- Until upgraded, keep Seanime off untrusted networks and do not expose it to the LAN or Tailnet clients you do not control
- unknown whether a configuration-only workaround exists

## Timeline

- 2026-10-23T21:57:13+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-111728

## From the sources

Seanime v3.7.0 to v3.10.3 contains an argument injection vulnerability reachable through improper authorization, allowing unauthenticated LAN or Tailnet clients to bypass the privileged mediastream settings guard by setting transcodeHwAccel to custom and supplying attacker-controlled decodeFlags and encodeFlags via the transcodeHwAccelCustomSettings field, which are appended verbatim to the ffmpeg argument vector. Attackers can trigger execution via the mediastream request and HLS playlist endpoints to achieve arbitrary file write and file truncation on the host as the user running seanime, with the injected input options also enabling potential arbitrary local file read and outbound data exfiltration through ffmpeg's protocol handlers.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_