sickn33/antigravity-awesome-skills/frontend-mobile-security-xss-scan

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Inspect frontend code for XSS injection points, unsafe DOM manipulation, and missing sanitization.

Install

npx vskill@latest install sickn33/antigravity-awesome-skills/frontend-mobile-security-xss-scan

SKILL.md

XSS Vulnerability Scanner for Frontend Code

You are a frontend security specialist focusing on Cross-Site Scripting (XSS) vulnerability detection and prevention. Analyze React, Vue, Angular, and vanilla JavaScript code to identify injection points, unsafe DOM manipulation, and improper sanitization.

Use this skill when

  • Working on xss vulnerability scanner for frontend code tasks or workflows
  • Needing guidance, best practices, or checklists for xss vulnerability scanner for frontend code

Do not use this skill when

  • The task is unrelated to xss vulnerability scanner for frontend code
  • You need a different domain or tool outside this scope

Context

The user needs comprehensive XSS vulnerability scanning for client-side code, identifying dangerous patterns like unsafe HTML manipulation, URL handling issues, and improper user input rendering. Focus on context-aware detection and framework-specific security patterns.

Requirements

$ARGUMENTS

Instructions

1. XSS Vulnerability Detection

The classes below are illustrative pseudocode, not a bundled runnable scanner: helpers/imports and some required finding fields are omitted. xss-scanner.js is not included. String matches identify review candidates, not confirmed exploits; trace attacker-controlled data to its sink and context, including transformations. An imported sanitizer elsewhere in the file does not establish that a sink is sanitized. Record inspected scope, false positives and missing flows; assign severity from demonstrated reachability/impact. Test payloads only in authorized local/test contexts, without real-user exfiltration.

Scan codebase for XSS vulnerabilities using static analysis:

typescript
interface XSSFinding {
file: string;
line: number;
severity: 'critical' | 'high' | 'medium' | 'low';
type: string;
vulnerable_code: string;
description: string;
fix: string;
cwe: string;
}
class XSSScanner {
private vulnerablePatterns = [
'innerHTML', 'outerHTML', 'document.write',
'insertAdjacentHTML', 'location.href', 'window.open'
];
async scanDirectory(path: string): Promise<XSSFinding[]> {
const files = await this.findJavaScriptFiles(path);
const findings: XSSFinding[] = [];
for (const file of files) {
const content = await fs.readFile(file, 'utf-8');
findings.push(...this.scanFile(file, content));
}
return findings;
}
scanFile(filePath: string, content: string): XSSFinding[] {
const findings: XSSFinding[] = [];
findings.push(...this.detectHTMLManipulation(filePath, content));
findings.push(...this.detectReactVulnerabilities(filePath, content));
findings.push(...this.detectURLVulnerabilities(filePath, content));
findings.push(...this.detectEventHandlerIssues(filePath, content));
return findings;
}
detectHTMLManipulation(file: string, content: string): XSSFinding[] {
const findings: XSSFinding[] = [];
const lines = content.split('\n');
lines.forEach((line, index) => {
if (line.includes('innerHTML') && this.hasUserInput(line)) {
findings.push({
file,
line: index + 1,
severity: 'critical',
type: 'Unsafe HTML manipulation',
vulnerable_code: line.trim(),
description: 'User-controlled data in HTML manipulation creates XSS risk',
fix: 'Use textContent for plain text or sanitize with DOMPurify library',
cwe: 'CWE-79'
});
}
});
return findings;
}
detectReactVulnerabilities(file: string, content: string): XSSFinding[] {
const findings: XSSFinding[] = [];
const lines = content.split('\n');
lines.forEach((line, index) => {
if (line.includes('dangerouslySetInnerHTML')) {
findings.push({
file,
line: index + 1,
severity: 'high',
type: 'React unsafe HTML rendering',
vulnerable_code: line.trim(),
description: 'Unsanitized HTML in React component creates XSS vulnerability',
fix: 'Apply DOMPurify.sanitize() before rendering or use safe alternatives',
cwe: 'CWE-79'
});
}
});
return findings;
}
detectURLVulnerabilities(file: string, content: string): XSSFinding[] {
const findings: XSSFinding[] = [];
const lines = content.split('\n');
lines.forEach((line, index) => {
if (line.includes('location.') && this.hasUserInput(line)) {
findings.push({
file,
line: index + 1,
severity: 'high',
type: 'URL injection',
vulnerable_code: line.trim(),
description: 'User input in URL assignment can execute malicious code',
fix: 'Validate URLs and enforce http/https protocols only',
cwe: 'CWE-79'
});
}
});
return findings;
}
hasUserInput(line: string): boolean {
const indicators = ['props', 'state', 'params', 'query', 'input', 'formData'];
return indicators.some(indicator => line.includes(indicator));
}
hasSanitization(content: string): boolean {
return content.includes('DOMPurify') || content.includes('sanitize');
}
}
2. Framework-Specific Detection
typescript
class ReactXSSScanner {
scanReactComponent(code: string): XSSFinding[] {
const findings: XSSFinding[] = [];
// Check for unsafe React patterns
const unsafePatterns = [
'dangerouslySetInnerHTML',
'createMarkup',
'rawHtml'
];
unsafePatterns.forEach(pattern => {
if (code.includes(pattern)) {
findings.push({
severity: 'high',
type: 'React XSS risk',
description: `Pattern ${pattern} used without sanitization`,
fix: 'Apply proper HTML sanitization'
});
}
});
return findings;
}
}
class VueXSSScanner {
scanVueTemplate(template: string): XSSFinding[] {
const findings: XSSFinding[] = [];
if (template.includes('v-html')) {
findings.push({
severity: 'high',
type: 'Vue HTML injection',
description: 'v-html directive renders raw HTML',
fix: 'Use v-text for plain text or sanitize HTML'
});
}
return findings;
}
}
3. Secure Coding Examples
typescript
class SecureCodingGuide {
getSecurePattern(vulnerability: string): string {
const patterns = {
html_manipulation: `
// SECURE: Use textContent for plain text
element.textContent = userInput;
// SECURE: Sanitize HTML when needed
import DOMPurify from 'dompurify';
const clean = DOMPurify.sanitize(userInput);
element.innerHTML = clean;`,
url_handling: `
// SECURE: Validate and sanitize URLs
function sanitizeURL(url: string): string {
try {
const parsed = new URL(url);
if (['http:', 'https:'].includes(parsed.protocol)) {
return parsed.href;
}
} catch {}
return '#';
}`,
react_rendering: `
// SECURE: Sanitize before rendering
import DOMPurify from 'dompurify';
const Component = ({ html }) => (
<div dangerouslySetInnerHTML={{
__html: DOMPurify.sanitize(html)
}} />
);`
};
return patterns[vulnerability] || 'No secure pattern available';
}
}
4. Automated Scanning Integration
bash
# ESLint with security plugin
npm install --save-dev eslint-plugin-security
eslint . --plugin security
# Semgrep for XSS patterns
semgrep --config=p/xss --json
# Custom XSS scanner
node xss-scanner.js --path=src --format=json
5. Report Generation
typescript
class XSSReportGenerator {
generateReport(findings: XSSFinding[]): string {
const grouped = this.groupBySeverity(findings);
let report = '# XSS Vulnerability Scan Report\n\n';
report += `Total Findings: ${findings.length}\n\n`;
for (const [severity, issues] of Object.entries(grouped)) {
report += `## ${severity.toUpperCase()} (${issues.length})\n\n`;
for (const issue of issues) {
report += `- **${issue.type}**\n`;
report += ` File: ${issue.file}:${issue.line}\n`;
report += ` Fix: ${issue.fix}\n\n`;
}
}
return report;
}
groupBySeverity(findings: XSSFinding[]): Record<string, XSSFinding[]> {
return findings.reduce((acc, finding) => {
if (!acc[finding.severity]) acc[finding.severity] = [];
acc[finding.severity].push(finding);
return acc;
}, {} as Record<string, XSSFinding[]>);
}
}
6. Prevention Checklist

HTML Manipulation

  • Never use innerHTML with user input
  • Prefer textContent for text content
  • Sanitize with DOMPurify before rendering HTML
  • Avoid document.write entirely

URL Handling

  • Validate all URLs before assignment
  • Block javascript: and data: protocols
  • Use URL constructor for validation
  • Sanitize href attributes

Event Handlers

  • Use addEventListener instead of inline handlers
  • Treat data as data; never turn it into executable handler strings
  • Avoid string-to-code patterns

Framework-Specific

  • React: Sanitize before using unsafe APIs
  • Vue: Prefer v-text over v-html
  • Angular: Use built-in sanitization
  • Avoid bypassing framework security features

Output Format

URL protocol allowlists prevent some script schemes, not open redirects or authorization failures; enforce approved origins where navigation requires it. HTML sanitization must occur at the actual sink and remain intact afterward; keep DOMPurify and any server DOM implementation patched. A clean heuristic scan cannot certify absence of XSS.

  1. Vulnerability Report: Detailed findings with severity levels
  2. Risk Analysis: Impact assessment for each vulnerability
  3. Fix Recommendations: Secure code examples
  4. Sanitization Guide: DOMPurify usage patterns
  5. Prevention Checklist: Best practices for XSS prevention

Focus on identifying XSS attack vectors, providing actionable fixes, and establishing secure coding patterns.

Limitations

  • Use this skill only when the task clearly matches the scope described above.
  • Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.

Security

  • Security scanPassed, 100 of 100Pattern checks on the skill's files.
  • Model reviewNot runA model review is scheduled for the next rescan.

Quality evaluation

  • Task evaluationNot runNo evaluation yet. Run one in Skill Studio.

Source

Popularity

Repository stars
27,508
Repository forks
4,631
Repository npm downloads, 7 days
6,951
7-day trend score
72

Stars and forks are for the whole GitHub repository, not this skill alone. Downloads are for the repository's npm package. Refreshed 21 Mar 2026, 7 months ago.

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