wrdn-code-execution

A security review guide for finding cases where user-controlled data can reach code or command execution on a server. It covers risks such as shell injection, unsafe deserialization, server-side template injection, and dangerous uses of eval-like tools.

In plain words
What is it for?
Use it to review application code for vulnerabilities that could let an attacker run commands or code on the server.
Why use it?
It helps distinguish real server-side code-execution paths from code that only looks dangerous by tracing untrusted input to the final operation.

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/getsentry/warden-skills/wrdn-code-execution
Any agent
npx skills add getsentry/warden-skills --skill wrdn-code-execution
Clone the repo
git clone --depth 1 https://github.com/getsentry/warden-skills

Made for: Claude Code, Codex.

Per session 102 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,003 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 1 finding. 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 $0.00102 $0.04003
Opus 5 $0.00051 $0.02001
Sonnet 5 $0.00020 $0.00801
Haiku 4.5 $0.00010 $0.00400

Measured 3d ago against content hash a775fa05db07, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

wrdn-code-execution scanned grade A with 1 finding 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 3d 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.

Runs shell commandslowCapability

Expected in a hook, worth knowing in a rule or an instructions file.

- **Identify the sink.** Is it actually dangerous in the form used? `subprocess.run(["ls", user_arg])` is safe. `subprocess.run(f"ls {user_arg}", shell=True)` is not.
skills/wrdn-code-execution/SKILL.md · 320 lines

How it starts

The opening of the file, as written. The whole thing — 320 lines — stays where its author put it; the contents beside it link to each section on GitHub.

You are a senior application security engineer. You hunt bugs where untrusted input reaches a sink that executes code on the server. These are high-impact bugs: they produce the attacker a shell, a new privilege, or the ability to pivot to credential theft.

The abstract shape is constant across languages:

untrusted source ──▶ (missing validation / unsafe API) ──▶ code-execution sink

This skill covers cases where the primary impact is arbitrary code or commands executing. Some sinks straddle multiple impact classes: XXE can read files or reach RCE gadgets, and command injection can exfiltrate files. Report here only when the code-execution path is concrete.

Trace. Do Not Skim.

The sink tells you what could happen. The source tells you whether it will. Trace before reporting.

  • Identify the sink. Is it actually dangerous in the form used? subprocess.run(["ls", user_arg]) is safe. subprocess.run(f"ls {user_arg}", shell=True) is not.
  • Identify the source. Values from request.body, request.query, request.headers, parsed webhook payloads, third-party API responses, file uploads, user-controlled config are untrusted. Hardcoded constants and server-side-derived values are not.
  • Trace the path. Read the function, the caller, and whatever validation sits between. A Pydantic schema with strict types may sanitize the sink argument; a Zod z.string() with no regex may not.
  • Check the library version. yaml.load without SafeLoader on PyYAML < 5.1 is unsafe by default. jsonwebtoken.verify before 9.0 allows algorithm confusion. vm2 in any version is abandoned and RCE-prone.
  • Use the shell. git log -p <file> shows whether a validation step was recently removed. rg -n '<sink>' enumerates siblings so you can compare the analysis.
  • Detect the framework. Load the matching reference for framework-specific idioms and defaults.

If the trace cannot be completed with the files at hand, drop the finding or report with lower confidence.

Read the full file on GitHub · 320 lines

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. 3d ago First seen · 320 lines · 102 tokens per session scan A a775fa05db07

Subscribe to this mod's changes

wrdn-code-execution is a skill published in the GitHub repository getsentry/warden-skills (57 stars, last pushed 11d ago), licensed MIT. It adds 102 tokens to every session and 4,003 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 1 finding (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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