youtube-downloader
Download YouTube videos and HLS streams (m3u8) from platforms like Mux, Vimeo, etc. using yt-dlp and ffmpeg. Use this skill when users request downloading videos, extracting audio, handling protected streams with authentication headers, or troubleshooting download issues like nsig extraction failures, 403 errors, or cookie extraction problems.
87
88%
Does it follow best practices?
Impact
78%
1.59xAverage score across 3 eval scenarios
Risky
Do not use without reviewing
Security
3 findings — 1 high severity, 2 medium severity. You should review these findings carefully before considering using this skill.
W007: Insecure credential handling detected in skill instructions
What this means
The skill handles credentials insecurely by requiring the agent to include secret values verbatim in its generated output. This exposes credentials in the agent’s context and conversation history, creating a risk of data exfiltration.
Why it was flagged
Insecure credential handling detected (high risk: 1.00). The skill explicitly instructs copying browser cookies and authentication headers from DevTools into yt-dlp/ffmpeg command lines (e.g., using --cookies-from-browser, --cookies-file, and -headers), which requires embedding session/cookie/token values verbatim in generated commands and thus risks secret exfiltration.
W011: Third-party content exposure detected (indirect prompt injection risk)
What this means
The skill exposes the agent to untrusted, user-generated content from public third-party sources, creating a risk of indirect prompt injection. This includes browsing arbitrary URLs, reading social media posts or forum comments, and analyzing content from unknown websites.
Why it was flagged
Third-party content exposure detected (high risk: 0.90). The skill explicitly fetches and parses metadata, thumbnails, and stream playlists from arbitrary public video URLs (YouTube, Mux, Vimeo, arbitrary m3u8) — see SKILL.md "Default flow" step 2, the HLS Stream Downloads section, and the Agent Execution Checklist — and the implementation in scripts/download_video.py (calls yt-dlp, urlopen/oEmbed, and ffmpeg) uses that untrusted third‑party content to decide retries, cookie/PO‑token flows, player clients, and other actions, so external content can materially influence tool use and next steps.
W012: Unverifiable external dependency detected (runtime URL that controls agent)
What this means
The skill fetches instructions or code from an external URL at runtime, and the fetched content directly controls the agent’s prompts or executes code. This dynamic dependency allows the external source to modify the agent’s behavior without any changes to the skill itself.
Why it was flagged
Potentially malicious external URL detected (high risk: 0.90). The skill auto-starts and installs remote components at runtime — e.g., it runs pip install using the PYPI_MIRROR "https://pypi.tuna.tsinghua.edu.cn/simple" to fetch packages like bgutil-ytdlp-pot-provider and executes "docker run brainicism/bgutil-ytdlp-pot-provider" to pull and run a remote container, which fetches and executes external code required by the default flow.
- Repository
- fernandezbaptiste/claude-code-skills
- Commit
4f0eae8
- Audited
- Security analysis
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