security-patcher

A security-fix procedure for patching vulnerabilities in a code repository.

In plain words
What is it for?
Use it when repairing a reported security weakness and preparing the affected file or patch for review.
Why use it?
It provides a required order for checking security reports, establishing a test baseline, gathering patch context, and preparing a fix. This helps avoid changing code without understanding the reported vulnerability.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/gemini-cli-extensions/security/security-patcher
Any agent
npx skills add gemini-cli-extensions/security --skill security-patcher
Clone the repo
git clone --depth 1 https://github.com/gemini-cli-extensions/security

Made for: Claude Code, Codex.

Per session 38 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 534 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What 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.

ModelPer sessionOnce invoked
Fable 5 $0.00038 $0.00534
Opus 5 $0.00019 $0.00267
Sonnet 5 $0.00008 $0.00107
Haiku 4.5 $0.00004 $0.00053

Measured 2d ago against content hash fe7d8696f9cc, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

security-patcher 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 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.

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.

skills/security-patcher/SKILL.md · 31 lines

What it actually says

You are a security expert. Your task is to patch security vulnerabilities in the user's code. Proceed with the following instructions using the context provided by the security_patch_context tool. Do not use any other context.

Your Steps:

  1. Pre-Requisites:

    • Check for the existence of a security report in the .gemini_security/ directory.
    • If a security report does not exist, kick off a security:analyze scan to build the required security context before proceeding.
    • Identify and run the repository's existing test suite (e.g., npm test, pytest, go test ./...) to establish a working baseline. This proves the environment is healthy before you attempt to write a patch.
  2. Gather Context:

    • Use the security_patch_context tool to retrieve the specific context for the patch.
  3. Analyze and Prepare Patch:

    • Analyze the file content and the associated knowledge base rules returned from the context.
    • Apply the secure coding patterns from the knowledge base to formulate a fix for the vulnerability in the target file.
    • Output the complete fixed file content or a patch for the user to review.
  4. Confirm Verification Intent:

    • Use the ask_user tool to ask if they would like to verify the patch (Yes/No). If No, skip to step 5 (Apply Patch to Target File).
  5. Verify the Vulnerability Exists (Before Patching):

    • If a PoC doesn't exist, use the security:setup_poc tool to generate one.
    • Execute the PoC using the run_poc tool before applying your patch to confirm that the vulnerability is reproducible.
  6. Apply Patch to Target File:

    • Apply your generated patch to the target vulnerable file.
  7. Verify the Vulnerability is Fixed (After Patching):

    • If you generated or verified a PoC in Step 4, execute the PoC again using the run_poc tool after applying your patch.
    • Analyze the output to confirm the vulnerability is fixed and the patch did not break the file's primary functionality.
    • Run any existing test files to ensure the patch did not break the file's primary functionality.
Changes

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.

  1. 2d ago First seen · 31 lines · 38 tokens per session scan A fe7d8696f9cc

Subscribe to this mod's changes

security-patcher is a skill published in the GitHub repository gemini-cli-extensions/security (791 stars, last pushed 1mo ago), licensed Apache-2.0. It adds 38 tokens to every session and 534 once invoked, about $0.0002 per session on Opus 5. 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.