Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add rules/ivangrynenko/cursorrules/javascript-injectiongit clone --depth 1 https://github.com/ivangrynenko/cursorrulesWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00000 | $0.01984 |
| Opus 5 | $0.00000 | $0.00992 |
| Sonnet 5 | $0.00000 | $0.00397 |
| Haiku 4.5 | $0.00000 | $0.00198 |
Grade A, and why
javascript-injection scanned grade A with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Unrestricted tool accesslowExcessive agency
A wildcard tool grant or "run any command" leaves no least-privilege boundary at all.
Impact: Attackers can execute arbitrary code in your application context. Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.
Runs shell commandslowCapability
Expected in a hook, worth knowing in a rule or an instructions file.
// Use child_process.execFile with separate arguments Copies of this mod
1 near-identical copy found in the catalogue:
- javascript-injection — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 217 lines — stays where its author put it; the contents beside it link to each section on GitHub.
JavaScript Injection Security Rule
actions:
- type: enforce
conditions:
-
pattern: "eval\(([^)](req|request|query|param|user|input)[^)])\)" severity: "critical" message: | 🔴 CRITICAL: Potential code injection vulnerability detected.
Impact: Attackers can execute arbitrary code in your application context. CWE Reference: CWE-95 (Improper Neutralization of Directives in Dynamically Evaluated Code)
❌ Insecure: eval(req.body.data)
✅ Secure Alternative: // Use safer alternatives like JSON.parse for JSON data try { const data = JSON.parse(req.body.data); // Process data safely } catch (error) { // Handle parsing errors } learn_more_url: "https://owasp.org/www-community/attacks/Direct_Dynamic_Code_Evaluation_Eval_Injection"
-
pattern: "\$\(\s*(['"])<[^>]+>\1\s*\)" severity: "high" message: | 🟠 HIGH: jQuery HTML injection vulnerability detected.
Impact: This can lead to Cross-Site Scripting (XSS) attacks. CWE Reference: CWE-79 (Improper Neutralization of Input During Web Page Generation)
❌ Insecure: $("" + userProvidedData + "")
✅ Secure Alternative: // Create element safely, then set text content const div = $(""); div.text(userProvidedData); learn_more_url: "https://cheatsheetseries.owasp.org/cheatsheets/jQuery_Security_Cheat_Sheet.html"
-
pattern: "document\.write\(|document\.writeln\(" severity: "high" message: | 🟠 HIGH: Potential DOM-based XSS vulnerability.
Impact: Attackers can inject malicious HTML/JavaScript into your page. CWE Reference: CWE-79 (Improper Neutralization of Input During Web Page Generation)
❌ Insecure: document.write("" + userGeneratedContent + "");
✅ Secure Alternative: // Use safer DOM manipulation methods const h1 = document.createElement("h1"); h1.textContent = userGeneratedContent; document.body.appendChild(h1); learn_more_url: "https://cheatsheetseries.owasp.org/cheatsheets/DOM_based_XSS_Prevention_Cheat_Sheet.html"
-
pattern: "innerHTML\s*=|outerHTML\s*=" pattern_negate: "sanitize|DOMPurify|escapeHTML" severity: "high" message: | 🟠 HIGH: Potential DOM-based XSS through innerHTML/outerHTML.
Impact: Setting HTML content directly can allow script injection. CWE Reference: CWE-79 (Improper Neutralization of Input During Web Page Generation)
❌ Insecure: element.innerHTML = userProvidedData;
✅ Secure Alternative: // Option 1: Use textContent instead for text element.textContent = userProvidedData;
// Option 2: Sanitize if HTML is required import DOMPurify from 'dompurify'; element.innerHTML = DOMPurify.sanitize(userProvidedData); learn_more_url: "https://cheatsheetseries.owasp.org/cheatsheets/DOM_based_XSS_Prevention_Cheat_Sheet.html"
-
pattern: "\$\(.*\)\.html\(" pattern_negate: "sanitize|DOMPurify|escapeHTML" severity: "high" message: | 🟠 HIGH: jQuery HTML injection risk detected.
Impact: Setting HTML content can lead to XSS vulnerabilities. CWE Reference: CWE-79 (Improper Neutralization of Input During Web Page Generation)
❌ Insecure: $("#element").html(userProvidedData);
-
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 217 lines · 1,984 tokens per session scan A 2320cdbcffa0
javascript-injection is a cursor rule published in the GitHub repository ivangrynenko/cursorrules (87 stars, last pushed 10mo ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,984 tokens. A static security scan graded it A with 2 findings (unrestricted tool access, runs shell commands). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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