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Purpose / Development

Web Design Guidelines Skill Security Audit

What the author says it does (original text)

Review UI code for Web Interface Guidelines compliance. Use when asked to "review my UI", "check accessibility", "audit design", "review UX", or "check my site against best practices".

Independent security check

Do not install or run it yet

Files checked
2
Risks found
1
Could it run dangerous commands?Looks for programs run straight after downloading, remote control of your computer, and hidden commands.No risks found
Could it expose your files or keys?Looks for uploads of files containing passwords or keys, and keys written directly in the code.No risks found
Could it delete files or keep running?Looks for broad file deletion, disk overwrites, and programs set to start automatically.No risks found
Could it bypass safety checks?Looks for skipped website security checks, excessive file access, or actions that skip your approval.No risks found
Could it mislead the AI or hide text?Checks the skill instructions for requests to ignore you, influence the report, or hide text in invisible characters.Risks found: 1
High risk

Each run trusts mutable remote instructions

Source references: 3
What we found

The Skill does not merely consult remote reference material; it explicitly treats “all the rules and output format instructions” in the downloaded file as instructions to follow. The URL targets the main branch without a pinned commit or content check, so a repository change or upstream compromise can alter the reviewing agent's behavior.

Why this matters

Malicious remote instructions could manipulate findings and output and, where the agent has the necessary capabilities, induce disclosure of reviewed file content, access to additional files, network activity, or other actions the user did not authorize. The supplied text does not show that any such action has occurred.

The Skill fetches mutable content from GitHub's `main` branch for every review and explicitly applies all of its rules and output-format “instructions” to the user's files. If the upstream repository, branch, or release process is compromised, that content could change the agent's review behavior, induce broader file access, or distort decisions. The evidence does not show that the current remote file is malicious, but it supports a supply-chain and remote-instruction risk. Users can ask for a pinned, reviewed commit with integrity checking, or require fetched text to be treated only as data.

SKILL.md:16In the instructionsOpen original file
1. Fetch the latest guidelines from the source URL below2. Read the specified files (or prompt user for files/pattern)3. Check against all rules in the fetched guidelines4. Output findings in the terse `file:line` format
Show 2 other places
SKILL.md:23In the instructionsOpen original file
Fetch fresh guidelines before each review:```https://raw.githubusercontent.com/vercel-labs/web-interface-guidelines/main/command.md```Use WebFetch to retrieve the latest rules. The fetched content contains all the rules and output format instructions.
SKILL.md:29In the instructionsOpen original file
Use WebFetch to retrieve the latest rules. The fetched content contains all the rules and output format instructions.
Could it change links or payment recipients without asking?Looks for forced referral or payment changes combined with instructions to hide the change.No risks found

Inside this skill

3 instruction sections

For every review, the Skill fetches current content from a GitHub Raw URL, reads the user-selected files, and applies all rules and output-format instructions supplied by that remote content.

View source
SKILL.md:16In the instructionsOpen original file
1. Fetch the latest guidelines from the source URL below2. Read the specified files (or prompt user for files/pattern)3. Check against all rules in the fetched guidelines4. Output findings in the terse `file:line` format
SKILL.md:23In the instructionsOpen original file
Fetch fresh guidelines before each review:```https://raw.githubusercontent.com/vercel-labs/web-interface-guidelines/main/command.md```Use WebFetch to retrieve the latest rules. The fetched content contains all the rules and output format instructions.

The repository records a source and Git SHA for the Skill synchronization, but review instructions are still fetched from a remote URL that is not pinned to that SHA, so this record does not lock the rules used on each run.

View source
SYNC.md:3In the instructionsOpen original file
- **Source:** `vendor/web-design-guidelines/skills/web-design-guidelines`- **Git SHA:** `5847a7c7e79bab3e400cf47800b83449d7aea2d4`- **Synced:** 2026-03-16
SKILL.md:23In the instructionsOpen original file
Fetch fresh guidelines before each review:```https://raw.githubusercontent.com/vercel-labs/web-interface-guidelines/main/command.md```Use WebFetch to retrieve the latest rules. The fetched content contains all the rules and output format instructions.
Start here · InstructionsSKILL.md
web-design-guidelines
Lines connect the instruction file to its sections, not an observed execution order. Select a section to read the source.
Files and check records2 files

Coverage and gaps

Content covered in each file

These are the source ranges included in this check, not a guarantee that every issue has been resolved.

  • SKILL.mdFull text included
  • SYNC.mdFull text included

This report is for the version above. We read the available code and instructions without running the skill or checking extra packages it installs. This is not a promise of safety: a different version or setup may behave differently.

  • SKILL.mdInstructions
  • SYNC.mdSupporting file

Operations mentioned in code and instructions

Read files
SKILL.md:17In the instructionsOpen original file
1. Fetch the latest guidelines from the source URL below2. Read the specified files (or prompt user for files/pattern)3. Check against all rules in the fetched guidelines
SKILL.md:35In the instructionsOpen original file
1. Fetch guidelines from the source URL above2. Read the specified files3. Apply all rules from the fetched guidelines
Connect to websites
SKILL.md:26In the instructionsOpen original file
```https://raw.githubusercontent.com/vercel-labs/web-interface-guidelines/main/command.md```
Lines read
46
File checksum (to compare versions)
336041ce54af8c617ff23b7d79d3e53cd4a4275c86ad067a06cf97947156503b