race-condition

race-condition is a skill for Claude Code, Codex from blacklanternsecurity/red-run. It costs 20 tokens per session (4,996 once invoked), scanned A, original, GPL-3.0.

A guide to testing race conditions and TOCTOU bugs in web applications. These occur when an application checks something and uses it later, leaving a small timing window for the state to change.

In plain words
What is it for?
It is for testing concurrent requests around payments, permissions, file operations, inventory, and other state changes.
Why use it?
It helps find flaws that appear only when requests happen at nearly the same time.

Skill for Claude CodeCodex

Which agent this was written for is unclear — body not stored (licence); the path alone says nothing.

Good fit It is for testing concurrent requests around payments, permissions, file operations, inventory, and other state changes.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/blacklanternsecurity/red-run/race-condition
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.

Any agent
npx skills add blacklanternsecurity/red-run --skill race-condition
Clone the repo
git clone --depth 1 https://github.com/blacklanternsecurity/red-run

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for race-condition

README.md
[![agentmods](https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/race-condition/github.svg)](https://agentmods.dev/skills/blacklanternsecurity/red-run/race-condition)
Your own site
<a href="https://agentmods.dev/skills/blacklanternsecurity/red-run/race-condition"><img src="https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/race-condition/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for race-condition

Your own site · 80×15
<a href="https://agentmods.dev/skills/blacklanternsecurity/red-run/race-condition"><img src="https://agentmods.dev/badge/skills/blacklanternsecurity/red-run/race-condition.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 20 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,996 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 2 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 5.1 $0.00020 $0.04996
Opus 5 $0.00010 $0.02498
Sonnet 5 $0.00004 $0.00999
Haiku 4.5 $0.00002 $0.00500

Measured 5d ago against content hash 10ead66e5b83, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

race-condition 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 5d 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.

Sends data to an external URLlowData exfiltration

A POST to an outside endpoint may be telemetry or may be exfiltration; either way the mod talks to somewhere, and you should know where.

curl -sI -X POST https://TARGET/api/transfer -d 'amount=100' \

Downgraded: this mod is about security review, or the phrase is quoted, so it is likely naming the pattern rather than instructing it.

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

- HTTP/2 support on target (for single-packet attack — check with `curl --http2`)
skills/web/race-condition/SKILL.md · 687 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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. 5d ago First seen · 687 lines · 20 tokens per session scan A 10ead66e5b83

Subscribe to this mod's changes

race-condition is a skill published in the GitHub repository blacklanternsecurity/red-run (267 stars, last pushed 5mo ago), licensed GPL-3.0. It adds 20 tokens to every session and 4,996 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 2 findings (sends data to an external url, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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