csp-bypass-advanced

csp-bypass-advanced is a skill for Claude Code, Codex from yaklang/hack-skills. It costs 52 tokens per session (3,228 once invoked), scanned A, original, MIT.

A security reference about weaknesses in Content Security Policy, a browser rule that limits where scripts, images, connections, and other content may load from.

In plain words
What is it for?
Use it when investigating XSS or data exfiltration blocked by CSP, including trusted endpoints, leaked nonces, policy gaps, or alternative channels.
Why use it?
It helps security testers understand why a policy may still allow cross-site scripting or data theft when trusted sources, nonces, or other policy gaps are misused.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is ├── Dangling markup injection → exfil without JS (see ../dangling-markup-injection/SKILL.md).

Good fit Use it when investigating XSS or data exfiltration blocked by CSP, including trusted endpoints, leaked nonces, policy gaps, or alternative channels.

Compare 6 skills from other repositories ↓
About the project

HackSkills is an organized knowledge base of installable skills that gives AI agents practical security knowledge across areas such as web security, privilege escalation, reverse engineering, and digital forensics. It is intended for bug bounty work, penetration testing, CTF competitions, and authorized security research. The catalogue entries are the project's own master, category, and topic skills.

yaklang/hack-skills · 2,143 stars · on GitHub

Install

Getting it into your agent

It runs from inside its repository, so the clone comes first — what it calls does not travel with the file alone.

Clone the repo
git clone --depth 1 https://github.com/yaklang/hack-skills
agentmods
npx agentmods add skills/yaklang/hack-skills/csp-bypass-advanced

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 csp-bypass-advanced

README.md
[![agentmods](https://agentmods.dev/badge/skills/yaklang/hack-skills/csp-bypass-advanced/github.svg)](https://agentmods.dev/skills/yaklang/hack-skills/csp-bypass-advanced)
Your own site
<a href="https://agentmods.dev/skills/yaklang/hack-skills/csp-bypass-advanced"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/csp-bypass-advanced/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 csp-bypass-advanced

Your own site · 80×15
<a href="https://agentmods.dev/skills/yaklang/hack-skills/csp-bypass-advanced"><img src="https://agentmods.dev/badge/skills/yaklang/hack-skills/csp-bypass-advanced.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 52 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,228 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • Socket warn 9 Apr 2026
  • Snyk fail 9 Apr 2026
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 3 findings, up to high

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • high YARA Match · line 3
    YARA rule matched a hack tool or exploit indicator (offensive tools, reconnaissance, privilege escalation, or exploit frameworks).
    Fix: Remove offensive tool references and exploit code. Legitimate agent skills should not contain penetration testing tools, exploit frameworks, or reconnaissance utilities.
  • high Prompt Injection · line 115
    Hidden instructions were detected in comments or invisible text. These could contain malicious directives. Manual review is recommended.
    Fix: Audit all comments and invisible characters. Remove any instructions that direct the agent to perform unauthorized actions. Use plain, reviewable content.
  • medium Excessive Agency · line 11
    Skill enables autonomous high-impact decisions without human-in-the-loop verification. Critical operations (destructive commands, financial transactions, data deletion) should require explicit user confirmation.
    Fix: Add human-in-the-loop confirmation for destructive, irreversible, or high-impact operations. Never auto-execute commands that modify files, send data, or alter system state.
How audits are shown
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 5.1 $0.00052 $0.03228
Opus 5 $0.00026 $0.01614
Sonnet 5 $0.00010 $0.00646
Haiku 4.5 $0.00005 $0.00323

Measured 10d ago against content hash 55bf3a08e10f, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

csp-bypass-advanced 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 10d 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.

Origin

Copies of this mod

4 near-identical copies found in the catalogue:

skills/csp-bypass-advanced/SKILL.md · 260 lines

How it starts

The opening of the file, as written. The whole thing — 260 lines — stays where its author put it; the contents beside it link to each section on GitHub.

SKILL: CSP Bypass — Advanced Techniques

AI LOAD INSTRUCTION: Covers per-directive bypass techniques, nonce/hash abuse, trusted CDN exploitation, data exfiltration despite CSP, and framework-specific bypasses. Base models often suggest unsafe-inline bypass without checking if the CSP actually uses it, or miss the critical base-uri and object-src gaps.


1. CSP DIRECTIVE REFERENCE MATRIX

Directive Controls Default Fallback
default-src Fallback for all -src directives not explicitly set None (browser default: allow all)
script-src JavaScript execution default-src
style-src CSS loading default-src
img-src Image loading default-src
connect-src XHR, fetch, WebSocket, EventSource default-src
frame-src iframe/frame sources default-src
font-src Font loading default-src
object-src <object>, <embed>, <applet> default-src
media-src <audio>, <video> default-src
base-uri <base> element No fallback — unrestricted if absent
form-action Form submission targets No fallback — unrestricted if absent
frame-ancestors Who can embed this page (replaces X-Frame-Options) No fallback — unrestricted if absent
report-uri / report-to Where violation reports are sent N/A
navigate-to Navigation targets (limited browser support) No fallback

Read the full file on GitHub · 260 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. 10d ago First seen · 260 lines · 52 tokens per session scan A 55bf3a08e10f

Subscribe to this mod's changes

csp-bypass-advanced is a skill published in the GitHub repository yaklang/hack-skills (2,143 stars, last pushed 2mo ago), licensed MIT. It adds 52 tokens to every session and 3,228 once invoked, about $0.0003 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.

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