Syncfusion aspnetmvc security

Skill syncfusion/aspnetmvc-ui-components-skills/skills/syncfusion-aspnetmvc-security

**CONTENT SECURITY POLICY (CSP) GUIDE** — Assist with configuring Syncfusion ASP.NET MVC EJ2 components to work with strict Content Security Policy (CSP) headers. Use when: implementing CSP headers, applying nonces to inline scripts/styles, configuring external font allowlists, or troubleshooting CSP violations and XSS protections.From its SKILL.md

Install

npx -y skills add syncfusion/aspnetmvc-ui-components-skills --skill syncfusion-aspnetmvc-security

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SKILL.md

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Content Security Policy (CSP) — Syncfusion ASP.NET MVC (Security)

Use this skill for high-level, Syncfusion-specific CSP guidance and vulnerability-free configurations. Detailed implementation patterns and troubleshooting live in the concern's references files.

When to Use

Implementing CSP headers for Syncfusion EJ2 controls in ASP.NET MVC
Running in strict CSP mode where inline scripts/styles are restricted
Blocking XSS, data injection, and other browser-based attacks
Allowlisting CDN resources, external fonts, and trusted origins
Validating and testing CSP compliance in development and production
Troubleshooting CSP violation errors in browser console

ASP.NET MVC-Specific CSP Implementation

Location: Meta tag in ~/Views/Shared/_Layout.cshtml head, or HTTP headers via IIS/code
Scope: Applied globally to all views; can be overridden per view if needed
Script Manager: Syncfusion's ScriptManager may require unsafe-inline mitigation via nonces

Key CSP Directives for Syncfusion

Core Directives Required

default-src 'self'                          // Restrict all to same origin
script-src 'self' 'unsafe-inline' https://cdn.syncfusion.com  // Scripts (inline needed for init)
style-src 'self' 'unsafe-inline' https://fonts.googleapis.com // Styles (inline for themes)
font-src 'self' data: https://fonts.gstatic.com https://fonts.googleapis.com // Fonts

Optional Directives

unsafe-eval (in script-src): Required ONLY if controls use templates (Grid, Dialog, etc.)
img-src: Add external CDN URLs if images hosted elsewhere
connect-src: For AJAX/fetch requests to data endpoints

Quick Checklist

✓ Add meta tag with strict CSP to _Layout.cshtml head
✓ Allow https://cdn.syncfusion.com for Syncfusion scripts/styles
✓ Allow https://fonts.googleapis.com and https://fonts.gstatic.com (Material/Tailwind themes)
✓ Include 'unsafe-inline' for style-src (Syncfusion uses inline styles for theming)
✓ Include 'unsafe-eval' in script-src ONLY if using template-based controls
✓ Test in browser DevTools (F12) → Console for CSP violations
✓ Monitor Content-Security-Policy-Report-Only for violation reports
✓ Avoid * wildcards; use explicit origins and 'self'
✓ Document any relaxations and security implications

Security Best Practices

Nonce Strategy: Generate unique nonce per request; apply to inline scripts/styles
Header vs Meta: Prefer HTTP header over meta tag for true enforcement
Violation Reporting: Use report-uri or report-to to monitor violations
Development vs Production: Use Content-Security-Policy-Report-Only in staging; validate before enforcing
Third-party Scripts: Audit Syncfusion CDN and trusted sources regularly
Minimize Inline Code: Refactor to external scripts where possible to reduce unsafe-inline scope

Common Violations & Fixes

Violation	Root Cause	Fix
Inline style blocked	Syncfusion theme styles	Add `'unsafe-inline'` to style-src
Font load failed	External font from googleapis	Add `https://fonts.googleapis.com` to font-src, style-src
Script init failed	ScriptManager inline setup	Add `'unsafe-inline'` to script-src or generate nonce
Template not rendering	Grid/Dialog template uses eval	Add `'unsafe-eval'` to script-src (with caution)

References

CSP meta tag & HTTP header examples: references/csp-guide.md

What ships with it: 1 file

23.3 KB alongside SKILL.md

references/

csp-guide.md23.3 KB

Gives 0 of the 12 instructions most security skills give in 791 tokens

Counted across 648 of the 828 authors here whose files we hold, read 2026-08-07

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Said here and by no other author read

add a strict Content Security Policy tag to the layout head
allow the component CDN in script-src and style-src directives
allow external font origins in font-src and style-src directives
include unsafe-inline in style-src for component theming
add unsafe-eval to script-src only when using template-based controls
check the browser console for Content Security Policy violations

Grouped from the skills themselves: near-identical wordings counted once, and counted by distinct author, so one author publishing three of these counts once. Length counted with cl100k_base; the agent that loads this file may tokenize it differently.