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/matank001/cursor-security-rules/secure-dev-rustgit clone --depth 1 https://github.com/matank001/cursor-security-rulesWhat 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 | $0.00470 |
| Opus 5 | $0.00000 | $0.00235 |
| Sonnet 5 | $0.00000 | $0.00094 |
| Haiku 4.5 | $0.00000 | $0.00047 |
Grade A, and why
secure-dev-rust scanned grade A with 0 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 yesterday.
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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 43 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Secure Rust Development
These rules apply to all Rust code in the repository and aim to prevent common security risks through disciplined use of memory safety, input validation, error handling, and safe APIs.
All violations must include a clear explanation of which rule was triggered and why, to help developers understand and fix the issue effectively. Generated code must not violate these rules. If a rule is violated, a comment must be added explaining the issue and suggesting a correction.
1. Avoid Unsafe Code
- Rule: Do not use
unsafeblocks unless absolutely necessary. If used, document the reason and ensure thorough review.
2. Validate All External Input
- Rule: All input from users, files, environment variables, or network must be validated for type, length, and format before use.
3. Handle Errors Explicitly
- Rule: Always handle
ResultandOptiontypes explicitly. Do not useunwrap()orexpect()on values that may contain errors orNone.
4. Prevent Integer Overflows
- Rule: Use checked arithmetic (
checked_add,checked_sub, etc.) or enable overflow checks in release builds.
5. Avoid Panics in Production
- Rule: Do not use code that may panic in production environments. Handle errors gracefully and return appropriate error messages.
6. Do Not Expose Sensitive Data
- Rule: Do not log or expose secrets, credentials, or personal data in error messages or logs.
7. Use Strong Types for Security-Critical Data
- Rule: Use newtype wrappers or strong types for authentication tokens, passwords, and other sensitive data to avoid accidental misuse.
8. Limit Use of Third-Party Crates
- Rule: Only use well-maintained and trusted crates. Regularly audit dependencies for vulnerabilities.
9. Avoid Dynamic Code Execution
- Rule: Do not use crates or patterns that allow dynamic code execution (e.g.,
proc_macro,eval-like behavior) with untrusted input.
10. Prefer Immutability
- Rule: Prefer immutable variables and data structures to reduce the risk of unintended side effects.
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.
- yesterday First seen · 43 lines · 470 tokens per session scan A 27dbb13c5300
secure-dev-rust is a cursor rule published in the GitHub repository matank001/cursor-security-rules (379 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 470 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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