Is Slack MCP server safe?
- Node.js network egress
- npm prepare hook
- MCP tool surface detected
@modelcontextprotocol/server-slack is an AI npm_package analyzed by SkillTotal's deterministic static scanner. The scan found no malicious indicators, though 3 risky constructs are reported for review. It can: install time execution, mcp tools detected and network egress — capabilities are what the code can do, not a verdict on intent. Risk score 0/100 (low).
@modelcontextprotocol/server-slack 2025.4.25
Automated static-analysis result. It can contain false positives and false negatives, and is not a claim about the intent of Slack MCP server's authors. Report a false positive.
Behavioral traits
How this component maps to the CSA agentic threat model. Descriptive — it never affects the risk score.
Findings (3)
package.json has a 'prepare' script (runs on git/local installs and before publishing).
"prepare": "npm run build",
Why it matters: Usually a build step, but confirm it doesn't fetch or run remote code.
Fix: Usually a legitimate build step; confirm it only builds and does not fetch or execute remote code.
The component makes outbound network requests.
const response = await fetch(`https://slack.com/api/conversations.list?${params}`, { headers: this.botHeaders });const response = await fetch(`https://slack.com/api/conversations.info?${params}`, { headers: this.botHeaders });const response = await fetch("https://slack.com/api/chat.postMessage", {const response = await fetch("https://slack.com/api/chat.postMessage", {const response = await fetch("https://slack.com/api/reactions.add", {const response = await fetch(`https://slack.com/api/conversations.history?${params}`, { headers: this.botHeaders });const response = await fetch(`https://slack.com/api/conversations.replies?${params}`, { headers: this.botHeaders });const response = await fetch(`https://slack.com/api/users.list?${params}`, {const response = await fetch(`https://slack.com/api/users.profile.get?${params}`, { headers: this.botHeaders });Why it matters: Usually legitimate, but confirm the destinations are expected and no sensitive data leaves.
Fix: Confirm the destination hosts are expected and that no sensitive data is sent off-host.
An MCP tool surface (manifest or tool definitions) was found.
const server = new Server({Why it matters: Just context — review which tools it offers and their permissions.
Fix: Review the declared MCP tools and their permissions.
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