Detect Web Race Condition
Detection and hunting methodology for web application race conditions: limit-overrun, multi-endpoint, single-endpoint, and time-sensitive flaws abused with last-byte-sync (HTTP/1.1) and single-packet (HTTP/2) request bursts to redeem a coupon or gift card twice, overdraw a balance, or defeat login, OTP, and MFA rate limits (MITRE ATT&CK T1190, and T1110 when the race defeats auth throttling). Works from reverse-proxy and load-balancer access logs, WAF logs, application event logs, and database error logs. Gives the burst and duplicate-success signatures, a hypothesis-driven hunt, and application-layer hardening. Use when investigating duplicate redemptions or double-spends, triaging a burst of near-simultaneous requests to one endpoint, hunting for single-packet or last-byte-sync race attacks, explaining why an idempotent endpoint produced two successes, or hardening payment, coupon, and auth flows against concurrency abuse.
Security AStatic scan found no risk patternsHow grading works ›
What this skill does
Detect Web Race Condition is a community-contributed Claude Code skill in the web-security sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/detect-web-race-condition/ and loads when your prompt matches the skill's trigger.
When to invoke it: Use when investigating duplicate redemptions or double-spends, triaging a burst of near-simultaneous requests to one endpoint, hunting for single-packet or last-byte-sync race attacks, explaining why an idempotent endpoint produced two successes, or hardening payment, coupon, and auth flows against concurrency abuse.
Who uses this skill
The Detect Web Race Condition Claude Code skill is built for security engineers, penetration testers, DevSecOps practitioners, and development teams hardening codebases and infrastructure. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 211,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).
How to install
Free
Manual install (2 steps)
mkdir -p ~/.claude/skills/detect-web-race-condition
curl -L https://claudskills.com/skills/detect-web-race-condition/SKILL.md \
-o ~/.claude/skills/detect-web-race-condition/SKILL.md
Or just download SKILL.md directly and drop it into ~/.claude/skills/detect-web-race-condition/. Claude Code auto-discovers it on next session.
Skills live at ~/.claude/skills/detect-web-race-condition/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\detect-web-race-condition\SKILL.md on Windows. See the full install guide for step-by-step instructions.
Telegram
📱 Install from your phone or desktop Telegram
Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →
Pro
One-click install via the desktop app
The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.
Pro
For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.
Frequently asked questions
How do I install the Detect Web Race Condition Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy
SKILL.md from the source repository to
~/.claude/skills/detect-web-race-condition/SKILL.md and restart Claude Code. Both flows are detailed at
claudskills.com/install/.
What does the Detect Web Race Condition skill do?
Detection and hunting methodology for web application race conditions: limit-overrun, multi-endpoint, single-endpoint, and time-sensitive flaws abused with last-byte-sync (HTTP/1.1) and single-packet (HTTP/2) request bursts to redeem a coupon or gift card twice, overdraw a balance, or defeat login, OTP, and MFA rate limits (MITRE ATT&CK T1190, and T1110 when the race defeats auth throttling). Works from reverse-proxy and load-balancer access logs, WAF logs, application event logs, and database error logs. Gives the burst and duplicate-success signatures, a hypothesis-driven hunt, and application-layer hardening. Use when investigating duplicate redemptions or double-spends, triaging a burst of near-simultaneous requests to one endpoint, hunting for single-packet or last-byte-sync race attacks, explaining why an idempotent endpoint produced two successes, or hardening payment, coupon, and auth flows against concurrency abuse.
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Detect Web Race Condition skill?
Use Detect Web Race Condition when your Claude Code task falls under the Security category — specifically in the web security area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Detect Web Race Condition" or describe the task and let Claude pick). Browse related skills at
/category/security/.
What is a Claude Code skill and how does the Detect Web Race Condition skill fit in?
A Claude Code skill is a
SKILL.md file that lives under
~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Detect Web Race Condition is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Security category. Learn more at
/learn/what-is-a-claude-skill/.
Attribution & license
Cite this skill
If you reference this skill in a blog post, paper, or documentation, you can cite it as:
APA
umbrasec-labs. (2026). Detect Web Race Condition [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/detect-web-race-condition/
BibTeX
@misc{detect-web-race-condition-2026,
author = {umbrasec-labs},
title = {Detect Web Race Condition [Claude Code skill]},
year = {2026},
publisher = {ClaudSkills},
url = {https://claudskills.com/skills/detect-web-race-condition/}
}Embed this skill
Promote, attribute, or link this skill from your own README, blog post, or documentation. All three snippets are free to use — no sign-up, no API key. More distribution surfaces →
Badge
[](https://claudskills.com/skills/detect-web-race-condition/?utm_source=badge&utm_medium=readme&utm_campaign=skill_badge)
<script>
<script src="https://claudskills.com/embed/detect-web-race-condition.js" async></script>
<iframe>
<iframe src="https://claudskills.com/embed/detect-web-race-condition.html" width="100%" height="160" frameborder="0" loading="lazy" title="ClaudSkills: Detect Web Race Condition"></iframe>
Security scan
Grade A · scanned 2026-10-25 — free static scan against the OWASP Agentic Skills Top 10.
No risk patterns were found in any of the ten OWASP-aligned categories. How grading works ›
- ✓ Prompt injection
- ✓ Data exfiltration
- ✓ Supply chain
- ✓ Reverse shell
- ✓ Credentials
- ✓ Execution
- ✓ Filesystem
- ✓ Persistence
- ✓ Obfuscation
- ✓ Network
Show this grade on your repo (click to copy):
[](https://claudskills.com/skills/detect-web-race-condition/#security)
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