Security Audit

coleam00/excalidraw-diagram-skill:root

github.com/coleam00/excalidraw-diagram-skill

AI SkillCommit 8646fcc9f74f

CAUTION

Scanned about 1 month ago

Critical

Immediate action required

High

Priority fixes suggested

Medium

Best practices review

Low

Acknowledged / Tracked

Trust Assessment

coleam00/excalidraw-diagram-skill:root received a trust score of 63/100, placing it in the Caution category. This skill has some security considerations that users should review before deployment.

SkillShield's automated analysis identified 2 findings: 1 critical, 0 high, 1 medium, and 0 low severity. Key findings include Unpinned Python dependency version, Headless Browser XSS leading to Local File Read/Data Exfiltration.

The analysis covered 4 layers: Manifest Analysis, Static Code Analysis, Dependency Graph, LLM Behavioral Safety. All layers scored 70 or above, reflecting consistent security practices.

Last analyzed on March 7, 2026 (commit 8646fcc9). SkillShield performs automated 4-layer security analysis on AI skills and MCP servers.

Layer Breakdown

Manifest Analysis

100%

Static Code Analysis

70%

Dependency Graph

93%

LLM Behavioral Safety

100%

Behavioral Risk Signals

Network Access

1 finding

Filesystem Write

1 finding

Shell Execution

1 finding

Dynamic Code

1 finding

Excessive Permissions

1 finding

Security Findings2

Severity	Finding	Layer	Location
CRITICAL	Headless Browser XSS leading to Local File Read/Data Exfiltration The `render_excalidraw.py` script loads a local HTML template (`render_template.html`) using the `file://` scheme. It then injects user-controlled Excalidraw JSON data into this page for rendering via `page.evaluate()`. If the Excalidraw rendering library or the `render_template.html` itself is vulnerable to Cross-Site Scripting (XSS) when processing malicious Excalidraw JSON (e.g., through unescaped text elements, embedded malicious SVGs, or external resource loading), an attacker could execute arbitrary JavaScript within the headless browser. Because the page is loaded via `file://`, this injected JavaScript would have access to the local filesystem, allowing it to read arbitrary local files (e.g., `/etc/passwd`, `~/.ssh/id_rsa`, sensitive configuration files) and potentially exfiltrate them to an attacker-controlled server. 1. Isolate Rendering Environment: Instead of loading `render_template.html` via `file://`, serve it via a minimal, ephemeral HTTP server (e.g., `http://localhost:port`) with a strict Content Security Policy (CSP) that disallows external network requests and local file access. This prevents injected JavaScript from accessing the local filesystem or exfiltrating data. 2. Strict Sandboxing: Ensure the Playwright browser is launched with the strongest possible sandboxing and security features enabled. 3. Audit Rendering Logic: Thoroughly review `render_template.html` and the Excalidraw rendering library's handling of user-provided content for XSS vulnerabilities. Ensure all user-provided text and embedded content are properly sanitized and escaped before being inserted into the DOM.	Static	references/render_excalidraw.py:128
MEDIUM	Unpinned Python dependency version Dependency 'playwright>=1.40.0' is not pinned to an exact version. Pin Python dependencies with exact versions where feasible.	Dependencies	references/pyproject.toml

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