T08 · Insecure Dependencies
- Location
SKILL.md:14- Finding
Unpinned Third-Party Package Execution Through npx
- Content
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Vulnerability Details
File Location:
SKILL.md, lines 14–23
Vulnerability Type: Insecure third-party dependency execution
Risk Level: MediumVulnerable Code
json { "mcpServers": { "plsreadme": { "command": "npx", "args": ["-y", "plsreadme-mcp"] } } }Technical Analysis
The recommended configuration invokes
npxwith the unversionedplsreadme-mcppackage and the-yoption. This permits npm to retrieve and execute the registry's current package version without interactive confirmation, an exact version constraint, integrity verification, or documented provenance validation.The reviewed package does not itself contain an embedded malicious script, and there is no evidence that
plsreadme-mcpis currently malicious. The weakness is a supply-chain trust issue: the effective executable can change after this Skill has been reviewed. If the npm package, publisher account, release process, or registry resolution path is compromised, users following these instructions could execute attacker-controlled code with the privileges of the MCP client process.Attack Path
- An attacker compromises the
plsreadme-mcppublisher account, release pipeline, or another relevant package-distribution component. - The attacker publishes a malicious release under the package name resolved by npm.
- A user copies the documented MCP configuration and starts or reloads the MCP client.
npx -y plsreadme-mcpretrieves the registry-selected release without requiring interactive approval.- Package installation hooks or runtime initialization code executes with the operating-system privileges and environment of the user running the MCP client.
- The malicious code can access resources available to that process and perform actions permitted by the user's account.
Impact Assessment
Successful exploitation can provide arbitrary code execution under the account running the MCP client. Depending on that account's ...[truncated 394 chars]
- An attacker compromises the
- Remediation
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Remediation Suggestions
- Replace the floating package reference with an exact, reviewed version, for example
plsreadme-mcp@X.Y.Z. - Install the dependency through a controlled project manifest and commit a lockfile containing resolved versions and integrity hashes rather than downloading a floating release at every launch.
- Verify the package's official npm namespace, source repository, maintainers, release provenance, and integrity before deployment.
- Avoid
-ywhere practical so unexpected installation or resolution behavior is not accepted automatically. - Prefer a preinstalled, reviewed executable referenced by an explicit local path.
- Run the MCP server in a sandbox or restricted account with minimal filesystem access, no unnecessary secrets in its environment, and constrained outbound network access.
- Establish an update process in which newer versions are reviewed and tested before the pinned version is changed.
- Replace the floating package reference with an exact, reviewed version, for example
